We're asking the same! Here's our situation as we are about to go full time.
We bought our SOB 5th wheel on Sept 4 and have traveled 140 nights by the end of May at 22 locations. We will go FT as soon as our house sells. We're ready! So far, we've used Passport, Good Sam and KOA. But where we visit the longest is near our daughter and our only grandson (now 9 mo old) in Fredericksburg, VA. There are only 3 places to stay and for us, the KOA is closest and the best. But there is a Coast to Coast (Presidential Wilderness-and has a sketchy reputation). Twice, we stayed one month at the KOA for $1000-this is the only location we'd stay longer than a few days and up to a month to help them out. Otherwise, we've been staying 3-6 days.
I just checked my KOA points and had like 40,000. So far, camped once for free on an over night stay. No one told me how many points a night costs. But I haven't really tried to find out.
So as we go full time, the $10-$19/night looks so attractive! And we plan to visit our grandson at least every 6 weeks-so need to determine cheapest way in the long run.
We just need FHU parking for our house on wheels as we go off sight-seeing/hiking or beach walking at each location
If anyone wants to see our travel list, let me know. I have it typed up on here as well as have a travel blog!