In reply to ShaunMc:
I stayed for a week in early jan a few years back. We stayed in Arinsal and had the Vallnord ski pass which covers you for 3 areas i think. The 3 resorts had easily enough to keep us occupied for a week (i'd say im intermediate ish, boarding red routes and skiing blacks). The slopes were'nt too busy either, nor were the lifts (no queuing at all)
The snow was fine, bit icy in the odd place but generally just the steep bits, and all the runs were open. Apres ski was good, decent food, and enough bars and clubs to keep you entertained. We stayed with a company called Hola-Andorra, very nice apartment and a 5 min walk from the main lift. Its also not too hard to get to from barcelona airport (we hired a car there, but i think you can get transfers easily enough if youre not doing a package)
I've got no complaints about the holiday whatsoever.