We also are considering Colorado for this Summer too. My wife went to WWW.Colorado.com and ordered their "free vacation guide." We've been deluged with literature from Colorado Tourism ever since. (and it's only been a couple months now). Those leaflets, booklets, and brochures sure are overwhelming. There's so much to see and do, it's hard to pin-point anything specific yet. Campgrounds are everywhere (so it seems).
My suggestion, go to their web site and explore it. Then order the free literature and sit back in your comfy recliner and enjoy reading one rainy night, or several rainy nights!