How do you begin to plan for extended road trips?

On the other hand. . . don't over-plan. Have some wiggle room for spur of the moment side trips of interesting things you might see or hear about on the way. When your trip plan says 'arrive CG XXX at 3 PM' and you decided to sleep in that morning and departed 4 hours late, you might be pushed too much. You are retired, relax and take it easy for a while. This is not a vacation where you have 14 days to get there, see the sites and return home.