Southern Colorado has an abundance of great locations, activities & RV parks. Most folks find that there is so much to do in the surrounding mountains, trails, lakes & rivers, that they spend very little time in the campground.
If you want to spend the month in one location, your first task is to choose from the 2 general areas of Durango/Silverton/Ouray vs Pagosa/South Fork/Creede . They both have nearby mountains, trails, lakes, rivers; but with minor differences in amount of people, tourism, & activities.
I stay in South Fork all summer, but take frequent short term trips to Durango, Silverton, Ouray, Pagosa, Gunnison, Buena Vista and Taylor Park; and enjoy them all for different activities and atmospheres. No shortage of good camp sites in all locations, but some do fill up early with long term occupants.