We go to Frisco, CO (a couple miles north of Breckenridge) every summer and it's one of my favorite places to visit. I highly recommend getting "The Complete Fly Fishing Guide For The Summit County Area" if you can find it. A great little fieldbook with tons of tips on where to fish, when to fish, what to use, and how to get there. I know I pull it out every year around the time we're heading up there. I second Ten Mile Creek, the Blue. I see a ton of people fishing the Blue in town so that is really close and the wading doesn't appear to be too bad. Summit country has some of the best fishing you'll find, IMO at least. I've also used Cutthroat Anglers for guide service and really enjoyed them.