We heading to the Dolomites for a week in September without a car. We are deciding whether to stay in Castelrotto the whole time and take the bus to Ortisei to try other hiking areas or to split our time between Castelrotto and Ortisei (or another town). Thank you for your thoughts!
I know the RS book recommends Castelrotto but I asked where to stay last year on the forum the recommendations were pretty unanimous for Ortisei. Ortisei has 3 lifts up into the mountains for hikes, Castelrotto has none. So every hike from Castelrotto will involve buses.
As your trip gets closer look up the activities offered including guided hikes on the https://www.valgardena-active.com/en website (summer activities probably aren't posted yet). We did several from Ortisei last year and they are free if your hotel is a Val Gardena partner which most are. They have hikes that start from other places as well.
I’d go with Ortisei or St. Christina or Selva in the Val Gardena. Not a fan of staying in Castelrotto. It’s on the outskirts.