We are going to start full time soon, and am looking to purchase a membership that would be the most comprehensive across the US. Do you have any suggestions of particular memberships that would be the best for nationwide usage?
Get one to Passport America. It is only priced at $44/year and you get half off of hundreds of RV parks all across the country as you travel. No doubt it is the best buy in discount camping and if you should happen to change your mind, simply do not renew as there is no membership that must be sold, like so many of the campground groups require.