Campgrounds near mountain biking in Colorado?

Been on the road for 7 years. First time heading to Colorado. Really interested in doing a lot of mtn biking while I'm there. Anyone know of any campgrounds near some good trails?

Mtn. biking aside -- favorite campgrounds in Colorado? Looking for a middle-of the road place. Up to $600/mo. Like wide-open space and views. And need to be w/in about 5 miles of a post office.

Really enjoy hot springs too.

Just me, no pets -- 36' fifth wheel.

Thanks!