How do you begin to plan for extended road trips?

When we retired in 2014, we decided to start leaving for the late winter/early spring, for sunnier/warmer climes. We are gone for 7-8 weeks and use Passport America and RV Park Reviews. We almost always make reservations since more and more Baby Boomers are doing the same thing.
Living out West, there's a lot of competition for campsites especially coastal ones, which are often booked year-round.