Staying at Walmarts and such

I'm new to this part of "camping", but I think I've got a good handle on what works and what doesn't (for us) now, after driving my new rig from Phoenix to Whitehorse in 8 days (staying at commercial and NPS parks, Walmart, a truck brake check area, and a viewpoint) and then a 4-day weekend in a small village near us. On the long trip I was making miles, had no need of services particularly (yes, electricity was handy), so really felt that the money I spent (highest was $46 at Grand Canyon) was basically for wi-fi, which of course I didn't "need". The NPS campground was $15 well spent simply for the location at Bryce Canyon. Our 4-day weekend was at a commercial campground within walking distance of everything we wanted to see and do, so at $18/night, a no-brainer, as there are no convenient-and-free options.