Although we love Hall in Tirol, it's not realy a "mountain" town and only 2 hours from Munich. Also, Castelrotto is nice, but not one we would stay at, especially with a car. I'd say any of the 3 villages of Val Gardena (Ortisei, St. Christina and Selva Gardena). The 3 villages are only 5 minutes drive from one another. We stayed in St. Christina at the Garni Ariston and would recommend it. There is a cable car from Ortisei to the Seiser Alm. Breathtaking scenery. There are trails which start from here as well as an outdoor/indoor resaurant/cafe. Since you'll have a car, drive to the end of the valley (not far at all) and take a ride over the Gardena and/or Sella Pass. Magnificent Dolomite vistas up close! Actually, even the drive from the Autostrada (I think A22) into Val Gardena is teriffic! Oh, it's only about 30 min. to get to Val gardena from the highway.