Fun Valley is the one that come's to mind if you're looking for places where there are lots of organized activities. But there's so much to do in SW Colorado, you may find plenty to do on your own. In fact, you might be better off picking a couple of places for two weeks each, as it would mean a lot of long days if you're wanting to see much of SW CO. Many of the roads are high speed, often with speed limits well below 55. For instance it's a minimum four hour drive one way from Fun Valley to Ouray, at that's assuming you don't stop for pictures or get stuck in slow traffic (very common with lots of RV's and semi's on these roads).
If you feel you must stay at only one CG for the month, I'd look at something around Durango, as it's somewhat centrally located. Durango also has more stores etc. than some of the smaller towns in the area. If you're there for a month, you should be able to meet others in the CG who maybe would like to join you in sightseeing in the area.