Since we are members of Thousand Trails, for the first 6 weeks of full timing, all but the first three nights when we stayed in a Passport America at 1/2 price they all have been "free". I mean if I stay in a Wallmart I still have paid my dues, if I stay in a Thousand Trails it cost me no more.
Having said that, in the past we have boondocked in the desert for a week at a time, stayed in Flying J's, Truck stops, and Walmarts.
Blessings,
Brian