By any chance are you planning this for a (British) uni ski trip?
I just got back from a uni trip there and I had a blast. We stayed in Pas De La Casa which is the furthest left most valley (on a piste map) and the town around there is really good for bars/clubs etc for evening times.
On that side of the valleys the skiing is good but quite flat and open (good for the beginners) but the park down there was more on the advanced side urban on rails, one box, and small kickers with the most retarded lip to knuckle distance and then some pretty big kickers that were a lot of fun.
If oh venture over to the El Tartare side of the mountain it gets more jibby with more trees and stuff and has a nice park that's a little more progressive then the Xavi park in Pas, and they also have their biggest park over there too.
The snow when we went was pretty good had a couple 5-10cm days and there's some really good terrain to be found if you go for a search, found some great trees with cliffs in etc. but has a really nice (from what I saw beginner set up)
I'd say if you've got beginners and want to party as well stay in the Pas side but if you're more for the skiing stay in the El Tartare side of things.
I also recommend getting to sunset park (where SLVSH is filmed although we didn't make it there) and to the 360 Freestyle centre which has a huge (and a smaller) kicker into a foam pit.
Andorra is also tax free so your fags and booze are dirt cheap.
I had a blast.
TL

R I would recommend skiing in Granvalaria from my one week uni trip there.