A great deal depends on the overall length of your RV. We spent last week going through campgrounds in California at US Forest Service and state park sites and most of them had a maximum length of 25 feet or less and as a result the campgrounds had 75% of the spaces available.
The longer the RV the fewer choices you will have and the more likely you will be paying 3-5 times as much to stay at a private RV park and will be much more limited on locations for you stays while traveling in many parts of the western USA.
For maximum flexibility a Class B or C motorhome that is 24' long or a slide-in camper on a pickup truck will provide the most options for the lifestyle you are proposing. Trailers are better suited for those who want to go to a place and stay for a week or longer and use it as a base of operations for day trips around an area.
