We will stay at a ORA (Outdoor Resorts Assoc.) park a couple of time per year. Like Aubrey said it is not for those on a travel budget. We look at it much the same as staying at a Hyatt vs a Days Inn; only we bring our own beds and glassware.
We have some significant limitations as to where we can stay in the RV due to length issues. The limit for many state parks and most "Big Rig" friendly RV parks is 40 feet; some parks are down to under 26 feet. Our 42 footer just won't fit or can't get into or out of many parks so we take advantage of the elbow room and the locations of several of the ORA parks.
Our favorite is Hilton Head, SC. Very tropical and lush. We go and feed the mosquitoes when we are in the area. We have also stayed in Las Vegas. Others to come as we are in the areas where they have these parks.
The rental costs are set by the local ORA park and are shared between the lot owner and the local ORA park. The owner also gets their utility bills paid while it is rented from the rental amount. Prime spots will get prime dollars so the rental is also higher. If you want to spend a LOT of time in one place purchasing a lot might pay off IF you can get it cheep and IF you can keep it rented. Even at that the payoff would have to be in appreciation rather than cash flow.
We actually own a lot in Hilton Head. We got it pretty cheap at the time. We have rented it a few times but not in a couple of months. The rentals are shifting to more of the "locals" with the insane fuel prices and this park is off the beaten track for most typical RV traffic. Also the parks limit rentals to only Class A or Class C coaches of a certain length. That also limits your potential renters.
We did not buy the lot to make money on it from rentals. We bought it because it was a place we wanted to spend a lot of time when we are on that side of the country and it is less than a full day's drive from my family. It gives us a lot of short trip options for day trips in the car which would cover a lot of major cities like Atlanta, Jacksonvile, Orlando, Tampa, Columbia, Charleston, Savannah, Wilmington, Raleigh, etc.
The lots in this resort are underpriced in comparison to other similar resorts in the area and across the country. If we screwed up at worst we have a place to stay for the price of electricity (the resort picks up the water and sewer costs). If not, then we have a potential appreciating asset we could sell in the future.