How do you folks plan travel for long distances?

For enroute DW will start searching in the afternoon depending on how many miles/hours we want to continue for that day. Sometimes we have been in some small RV park not on the map and sometimes KOA works. Have always found a spot without too much trouble. But I get it, we did more planning when the kid was young. While travelling we frequently see small half full parks along the way. We like to stop and have a place before dinner. Definitely prefer to have reservations at the popular destinations.