Some of these places offer to let you park for a few hours to get some sleep. My feelings on the use of Walmart and such places is in late and out early.
Remember that it is not a campground and we should not abuse the use of these places to get some shut-eye. You will see some treating it as a campground, slides out, jacks down, awning out, lawn chairs and the grill going. They will disconnect and take off site-seeing and leave the RV there.
There is no power, water or dump area. Leave it cleaner than you found it.
Some areas have ordinances which prohibit staying in an RV and can ticket you, or wake you up at 1:00 AM and tell you you have to move on. So watch for signs at the parking lot and be sure an ask as well.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot