If we have a particular destination, i.e. St. Augustine, FL, we generally make reservation for a site there for a couple of days. But to and from, which to us is an adventure in itself and generally takes several days each way and is a large part of the trip, is to plan park A, but also list park B & even C just in case for a night or two.
Our last trip to Texas Hill Country was the rule breaker. Virtually every State/COE park was booked for the weekend. Even forced us to spend the weekend at a private "RV Resort" much to our chagrin.
All in all it worked out to be pleasant, but not the same as a state or COE.
This was even mid April and not supposed to be crowded. Guess it's all those blasted baby boomers retiring and getting into RV'ing like us!