This is a basic guide to help you chose the right telescope for you. This is not an exhaustive list, but a collection of things I've learned over time.

WHAT TYPE OF TELESCOPE:

This is a summary of the 4 main types of telescope and their + and - points. It's mostly practicality advice and I have tried to keep my opinion out of it.

Newtonian Reflector:

+ Large aperture (more light in) is relatively cheap

+ No lenses so no colour fringe issues

+ Large range of sizes

+ Very little dew build up as there's no lens in the front of the tube

--

- Large aperture scopes are long too and can be cumbersome

- Bigger scopes are quite heavy due to the large lower mirror

- Needs a decent mount as length needs balance

- Eyepiece on side can be awkward to get to as it's at the front.

- Can catch on tripod at near-vertical orientations due to length

- For optimal performance the mirrors need collimating (aligning). This is straightforward but isn't usually required on other scopes

'Newts' are best for deep sky and wide field observation. They cope well with planetary observation but can almost capture too much light on bright objects and white out the disc a bit. I use a Skywatcher 8" x 1000mm Newt with a webcam for planetary photography (more below) for my observations and it's actually a little bit too large to use regularly.

Refractor:

+ Great for moon and planet observations 

+ Modern Apochromatic Refractors give almost perfect image (at a price)

+ Can be small and light weight

+ Many work well with DSLR setups, esp. better quality ones

+ Modern coated lenses improve scatter and increase incoming light

+ Eyepiece/focuser is at the end so you can nearly always get to it easily.

--

- Aperture makes them less good for deep space

- Lenses cause fringing and light scattering

- Cheaper Achromatic refractors suffer colour fringe

- Front lenses often dew up, even a dew shield will stop it only for a few hours, DON'T wipe it with a cloth, it scratches the coating!

- Large scopes are heavy and need a good mount/tripod

Refractors, unless very expensive and with high quality lens sets and a large aperture (into the $1000s there), are generally not that good for deep sky, but do well with planets and moon observation. A very high quality 80mm like the Skywatcher Equinox 80mm or a Orion ED80 will be superb for near-objects, but will start to suffer as you get into deeper space objects due to lack of aperture. It is generally felt that the ED80 style Apochromatic scopes are one of the best for DSLR work though, where light can be acquired over time.

Cassagrain:

A compromise between the above two, being lenses + mirrors.

+ Large aperture and short tube

+ Good balance of aperture and size

+ Short tube makes it perfect for GOTO motor systems

+ Not likely to hit the tripod

+ Eyepiece/focuser is at the back so it's easy to get to

+ Good all round balance

--

- Lenses cause fringing and light scattering - a lot less in a Cass. than a Reflector

- Front lenses can dew up, even a dew shield will stop it only for a few hours

DON'T wipe it with a cloth, it scratches the coating!

- Large scopes are still heavy and need a good mount/tripod

I've never used a Cass, they are effectively a middle of the road. It's an effective way to 'fold up' a Newtonian tube into a shorter scope and make it more convenient to use and view. Useful compromise and nice for most things, so I'm told. A lot of GOTO systems are sold with a Cass tube because it's short and stops it  smacking the mount/tripod at near-vertical objectives. 

Dosbonian:

+ Cheapest way to get large aperture for deep space

+ Dead simple

+ Modern Dobs are collapsible making moving long tubes easy

+ No fighting with Equatorial mounts

+ Dewing not a big problem, it's a Newtonian tube

--

- Bases can sometimes be a little unsteady

- Collapsible tubes sometimes can have alignment issues

- Not a lot of use for astrophotography - not stable enough

- Eyepiece can be awkward to get to on some larger models

John Dobson designed his telescope to be cheap and easy to make, and enable large aperture telescopes to be easily accessible to the public. Today this is still true, due to the relative simplicity of the Dobsonian design these are still affordable, powerful telescopes. They take next to no setting up and modern designs such as the truss-tube and collapsible variants are easy to transport. You can even buy Dobsonians with motor auto-tracking these days, so you can move it accurately and don't lose sight of the object in view.

I OWN/HAVE SEEN A SPOTTING SCOPE FOR GROUND USE - WILL THIS WORK?

Yep. Spotting scopes are pretty good for low magnification stuff, but bear in mind that ground scope optical and ground binoculars are generally not as accurate as astronomical ones. Generally colour fringing and light scattering tend to be a lot worse, so deep sky objects will not show up, but for looking at the moon and planets they can be pretty good.

WHAT ABOUT BINOCULARS?

A good set of binoculars is a very useful companion to a scope, but it can also be a very good observation tool on its own. Same goes as for Spotting Scopes. Optics for ground use are not generally up to detailed astronomy. Some companies do sets of Astronomy binoculars now however with more suitable optics. Many modern binoculars can also be tripod mounted too using a 90-degree adapter. This can be very useful for night sky observation.

OTHER THINGS TO CONSIDER:

Don't buy a nice shiny tube and skimp on the mount! A good sturdy and stable mount is crucial especially for long exposure photography. It's just convenient for manual observation to stop you knocking the system out of alignment.

Make sure the finder scope on the side is decent quality. They are usually a low magnification optical or a laser dot finder. As long as it works well (reasonable image etc), is stable and it's easy to align to the main scope it'll do the job.

Most good Skywatcher, Meade, Orion and Celestron telescopes come with 1 or 2 decent eyepieces, and some come with a Barlow lens, which can be used to multiply the eyepiece magnification. Good eyepieces and lenses are CRITICAL. There's no point in having an expensive scope and using crap lenses, lowest common denominator and all.

Don't buy something enormous that you struggle to get out all the time. It'll make you procrastinate and not go out. If it's already cold and dark you don't want to be moving masses of heavy gear to get the scope set up. Truth be told mine is too big really. I want a small scope for the nights when I can't be bothered to drag the large one out.

Sounds daft but carrying a good pair of binoculars as well as the scope can help a ton.. Being able to look 'freestyle' at the sky gives you a better sense of location so when you look at the sky in the scope or finder you can navigate more easily.

Modern motorised GoTo full motorised systems are a gem. Celestron and Skywatcher are the best about and they aren't nearly as expensive as they used to be. Even so they must be spirit levelled and setup correctly to work right.

If you have heavy duty camera tripods for film work you might be able to get a scope or a scope and mount block that will sit on that. Worth looking at. If you use a normal camera tripod you will lose the Equatorial tracking ability on the controls but it's a lot easier to steer.

Equatorial mounts are sometimes a bit frustrating to point at something. Equatorial mounts, however, have the advantage of being able to be fitted with motors for tracking. There again though, dedicated GOTO scopes are usually a conventional Alt../Azimuth type mount system because it can adjust X and Y values simultaneously. Pick your mount carefully...

The devil with kit like this is in the detail. If you can, check the quality of things like adjusters for mirrors, the smoothness and the tension on the focuser (is it smooth and will it stay put?). Is the overall build quality good enough to stand regular use?

ASTROPHOTOGRAPHY

Deep Space is best done using a DSLR. It allows you to play with shutter speeds and exposure etc. to get a good picture and allows you to get plenty of light into the camera. However, you will need accurately setup motor tracking to do long exposure deep-sky work. A GoTo setup would get you that as they auto-calibrate (and it works, most of the time!!). There are CCD cameras also that can do deep space photography but they are very expensive for the enthusiast, and should only be bought if you have a specific requirement for one.

Planetary photography is best done with a webcam. It has to be a good one with a good quality low-light CCD. I can go more into specific models and where to get them if you go down this route. A 1/25" eyepiece adapter and UV/IR cut filter are all you need and then it drops in the eyepiece hole in the focus. Recording is best done using software like WxAstroCapture, and post processing is done in Registax. The idea is to collect about 500-1000 frames of video and then stack them to create one image which, if conditions are right and you get it in focus, will yield a very nice sharp image, even when the frames in the raw video look nasty. Again, dedicated CCDs can do very good planetary photography but the cost os often prohibitive.

Don't get put off by the complexity of Astrophotography. It's not as bad as it looks and it VERY rewarding!

FOR THE KIDS

The key with kids is simplicity. Dobsonians are perfect for this. No mounts, no setup just plonk it on the lawn, pull out a star map and find your object. Stick to something sensibly small and lightweight, and cheap so if they break it it's not a showdown. If you want a tripod mount scope, a decent make of refractor is easiest to use and setup. Even something as simple as the Galileoscope that was sold this year for the International Year of Astronomy is enough to get going.

Start simple. Look at the moon. It's good practice and contrary to some people's belief there's LOADS to see on there. Craters, mountains, you can even point out where the Apollo moon landings touched down, although you'll have to tell them they won't see the lander from Earth! Move on to a bright planet next. Which planet depends on time of year etc. but there's usually one to look for. After that consider looking for some obvious deep sky objects, but bear in mind the capability of the telescope and how hard they are to find.

The important thing is  that you fuel kid's imaginations. If they ask to go look at the stars, there shouldn't be any practical astronomy reason for you to not be able to, it's way more powerful to be able to say 'yeah sure' or 'okay in an hour or so' and go out and look, than have to make excuses about taking time to setup etc. That'll make the kids think it's not a hard thing to do and make then keen to try for themselves.

You might want to also find them some kids’ books on the night sky and space to get them reading about it. Appreciating space and the night sky is something that will open all sorts of avenues of other science and interesting topics. It's a great mind expander for any person, especially kids.

I'M STILL CONFUSED!

If you want to discuss any details in this article with me I can be found on Twitter @MDBenson or by e-mail at md.benson@gmail.com - I will try to assist where I can!

Thanks to @Bellatrixlestar for help with proofing and editing the guide!