Rent a car for sure! I lived in Breck for 2 seasons. The thing about Summit county is that there are a ton of options. Sometimes Vail will get snow and Breck nada. A-Basin will be insane and Keystone is ice. The best thing to do is to keep your options open to get the freshies!! I personally would not go there without a car. It's cool to check out some of the other towns around S.C. too.