seasonal RV parks

First, which season? Second, Colorado is a pretty big state,so where are you interested in staying?

If summer, most Texans I have seen staying all season congregate in the Creede-Lake City part of the San Juans. Every RV park in that area seems to offer a monthly rate, although a few may have a longer rate.

If you are more interested in Colorado Springs or Estes Park, you may have a lot more difficulty finding one. Most of the private parks near me either have long-term RVs, meaning "permanent" and are not ones you would want to be in that long, or they primarily serve daily to weekly RVers and don't want long-term because they make more money during the busy summer season that way. For more info, see http://campcolorado.com/about-us/ (the Colorado Campground and Lodging Owners Association).

Almost any park will have seasonal rates. Best to go to some site like RVParkReviews and find the area you want then look at all of the parks in that area.