We're going on a 12-day trip to Italy in August, spending a week in a villa outside Trento and another several days in Venice. I am a big Winter Olympics fan. Is a day trip from Trento to Innsbruck realistic? Or from Trento to Cortina? We'll have a car.
Both are realitevely easy day trips from Trento with car. Innsbruck is 1h50 on the highway (it is a beautiful highway, though, mountains on both sides all the way to Austria). Cortina d'Ampezzo is 2h40 from Trento, and the route is absolutely stunning on itself. If you are going to Cortina d'Ampezzo, make sure you take different routes to and from there to enjoy different scenarios. Here is a suggested round-trip on Google Maps: http://goo.gl/maps/a54bQ
The only thing I would add is that the traffic between Trento and Innsbruck in summer along the Brenner Pass is usually very heavy. When I drove this route last summer, I think it took close to 3 hours due to long back-ups at the tolls.