Which is the better time (weather) to visit and do some day-hikes in the dolomites: mid-October or mid-May. besides wanting good weather, we also wish to avoid the most crowded times.
We'd expect snow on the ground to be more of an issue in mid-May. Snow could start by mid-October, but wouldn't yet be built up.
We are in the Val Gardena now and the crowds are thin, weather cool. One can never tell about October, but depending on the specific area you plan to visit, many lifts will be closing before mid-October and may not be open by mid-May. What specific area do you have in mind?
I would go in mid October, as we have a few times. I'd stay in the Val Gardena. The Mont Seuc Cable car trip from Ortisei to the beautiful Seiser Alm/Alpe di Siusi runs until early November. Also, the town wide market in Ortisei is on the second Monday of October. Fabulous event to attend.
Paul