I should probably clarify my previous post in this thread - While I rarely make reservations, I do plan my trips. I keep a folder on my laptop & add links to places that other travelers recommend, campgrounds that look interesting, and places that look interesting to visit. I make a Google map with markers for all the locations, then attempt to choose a route between the locations that uses as many scenic drives (and as few interstates) as possible.
I also agree with those suggesting arriving early. I rarely stop after 3:00, sometimes as early as 1:00. Of course I have the advantage that being retired, I'm in no hurry. I realize that many have to travel longer in order to get to a distant location in a short vacation period.