Hi Jay,
I think you're over thinking or over worrying. We've been to the Dolomites in mid October a couple of times. We've been to Switzerland (incl. the Berner Oberland) in mid October once. We've also been to the Austrian Alps and Bavaria in mid to late October a few times. If I could pick any month to visit any of these, it would always be October. If daytime temps in the low 60's (maybe high 50's) are going to keep you from having a good visit, skip the Dolomites. Weather is unpredictable. We once had a day in Brixen/Bressanone (45 min. from the Val Gardena) in the upper 70's/low 80's in October. We visited Zell am See the first of Nov. and it was a beautiful, mild day. Once in the Innsbruck area, in late April, we had a very nice day in Innsbruck, drove to the Stubaital and it was snowing, then drove back to the same nice day in Innsbruck. Our experiences.
We've also seen very little rain in October in all these places during all our visits.
Yes, hotels and B&B's will be open. Yes, restaurants will be open. Locals don't go out for dinner? Maybe not as many as in the high seasons, but for your 3 nights, there's no worries.
I'm not trying to talk you into a visit you're not sure of, but you did ask for opinion's and first hand experiences.
If interested, we stayed here in the Val Gardena:
www.garniariston.com
Paul