I just started this summer and love it! My wife is as much a maniac as I am! we have gone on Eagle Rock and Saran Wrap, Spring Creek, and several of the trails around the rampart range.
I preffer the rock crawling but enjoy just getting out of the city.
I recommend a good map and GPS - a lot of the trails are not really well marked.
My wife and I have an '04 Wrangler with a 5" lift and 33" tires. The closest place to go that isn't too crowded is Buena Vista. If you want some of the best trails in CO, take a weekend and go to the San Juans around Silverton, Ouray, and Telluride.
I've got a 2010 JK and love the access it gives me to remote camping areas. So far my favorite trail would have to be Hackett and Metberry Gulch. It ends when it reaches the Platte River and there's great camping/swimming/fishing there. China Wall is also nice with some streamside camping.