This question has come up before with various methods discussed. It depends on your style of travel, types of spots - commercial, State or National Parks, etc... We plan months in advance with reservations . We never travel more than 200 miles and always stay 2 or more nights. We like the no pressure of needing to leave early and arrive early to get a spot. With reservations the spot is there and no need to hurry. Many National Parks must be reserved well in advance as do some State Parks if in high demand areas or prime tourist season. Our 2015 travel is already booked thru mid September. Others wing it and claim to do fine, but in general are stopping very early in the day on travel days. You may try a combination until you find your groove. Good luck.