What I like about Val di Fassa is the access to smaller, less known and less crowded areas (ie NOT the Sella Ronda areas). Obereggen, Vigo di Fassa, Pozza di Fassa, Passo San Pellegrino, Alpe Lusia, Alpe Cermis, Civetta... If I had the choice, I would stay in Moena. Very nice town, central position in the valley to ski all areas above and also the Sella Ronda (Civetta is furthest @ 45 minutes, the rest is within 25 minutes by car), bus service is well organized too.
I have been to all these places multiple times.