In reply to mike123:
+1 more for the Lecht. You can reach it from Aviemore in under an hour, or as stated above, stay in Braemar (or even Ballater) and have both the Lecht and Glenshee as an option.
For kids and/or beginners, thet Lecht is excellent.The day lodge being right by the slopes is useful in poorer weather, and while the area is not the most extensive, for beginners it's more than enough terrain. It's also more sheltered from the wind than Cairngorm.
When looking for progression, Glenshee's large intermediate areas are a great next step, and the new Cairnwell chair has helped reduce queues across the mountain. Glenshee also has a lot of lifts so queuing is rarely a problem, and gives a great feeling of travelling around.
??If off slope, is important, you may find Nevis is better. Fort William is no Aviemore, but it does have a swimming pool, indoor bowlings & soft play (at Nevis Center) and an excellent bouldering/climbing wall at three wise monkeys (and Ice Factor is 40mins away at kinlochleven). It's slopes are more exposed in my view, but can be excellent in good weather. You can also reach Glencoe in similar time, but while its excellent, i'd say not the best for beginners unless the weather is nice and calm and the plateau has good cover.
If I'm honest, Cairngorm was always my last choice for a Scottish ski trip. It's furthest away from me, and on my rare visits was always too busy, or closed due to high winds on arrival.
I haven't been there in over five years (last year's attempt with a friend with local accomodation, was diverted to the Lecht due to, you've guessed it, closure due high winds).
Hope you have a great time wherever you go