Hi there. I have just come back from a skiing holiday in El Tarter Andorra. I would recommend you book through an agency (I did Thomas Cook), they then book you through a ski firm such as neilson ski or crytal ski. You can buy you flight, accom, transfer, ski pass and equipment in one and it is all sorted for you by the reps. Dead dead easy.
I would recommend Aparthotel del clos. Perfect for groups and families. half board, amazing food in the 4 star hotel it is attached to. Also complete access to pool, jacuzzi and steam room and games room with bowling ally! ( they are not paying me for this either! :P)
The ski pass includes all areas (pas de la casa, soldeu el tarter, canillo and encamp). The place i recommneded has the ski lift attached to it..
For everything (flight, accom, trnafer, food, ski pass and equipement) for a week I paid around £800. I only spent about £150 while i was there as well....cheap beer!
Soldeu is the biggest resort in the area and has more of a night life but to be honest by the time you come off the slopes you are pretty shattered.
hope this helps a bit!!