Many always respond with state, federal, and blm parks as being the best bet, don't stay at CG's etc., etc.
That works if you are destination RV'ing for a pre-planned weekend or vacation. BUT for a traveler RV'er, State/Fed parks within a given area or state are few. And many not be anywhere's near where you are traveling thru.
When you are traveling from point A to point B that takes several days snowbirding or full-timing - CG's are what is available, simply by the shear numbers of them versus state and fed Parks and proximity to the road you are traveling on. We are not going to travel 40 miles off the interstate to stay at a State Park.
And just for the record you'd be hard pressed to find BLM land in the Midwest, south or east. :W