My family is probably going to travel to Keystone or Boulder Colorado this summer. What r fun things 2 do?

I think the better choice would be Boulder in this situation. You are definitely a lot closer to Denver than you would be in Keystone so you are really able to visit both places. Plus, being in Boulder only puts you at about a 45 min drive from Estes Park as well which is a fun little mountain town. You can do a lot of out doorsy things in Boulder like hiking, mountain biking , stuff like that. Also a fun thing to do is to go tubing down Boulder creek. It gets fairly hot and nothing cools you off better than cruising down the creek. Pearl Street is great for eatting and shopping and the night life is pretty active even in the summer. Have fun!

Try the alpine slide in Keystone and lots of neat shops in Boulder Commons shopping area in the center of Boulder. You can also take a ski chair lift ride at the Keystone ski resort. Lots of fantastic moutain scenery for hiking in both Keystone and the Boulder areas. Mtn biking is big here too. Can't miss at either, but I'd say Keystone is a far better choice.

I agree with everyone else here. Four wheeling is fun around there. You can also drive up to Rocky Mountain National Park for a day which is totally worth it. Great camping place: Buchanan Pass forty miles west of Boulder.

Another fun thing to do in Boulder, (well, just outside Boulder), that hasn't been mentioned yet is to go see Boulder Falls. It's a short and easy hike to the falls and it's nice on a hot day since you can get close enough to it to feel the spray from it. Anyway, I'm giving you a link to some information about it. Have fun :-).