Allenspark is going to still be pretty damn cold this time of year since it pretty high altitude. Try the Poudre Canyon just west of Fort Collins or the Lyons area where it will be drier and warmer. Or you could go south down by Canon City where it would be even warmer.
i just finished my fifth night in a row camping. so tired, but if you happen to be around steamboat, seedhouse near clark is really nice. there is lots of places that you could bring a lot of people.
Nederland and Rollinsville have some sick spots if they are open yet. Lots of car camping, so it can be busy, but it is close to Boulder. If you want to hike you can find awesome stuff with the Divide just right infront of you.