Travel with 4 year old Grandson

We started taking our grandson with us on our MH trips when he was about four. His mom and dad work of course so I thought he might enjoy seeing the world with his grandparents. We've continued this every year since and each time we can get away he wants to go with us; he's almost 13 now. So far we've been to every state (except Hawaii) and Canada a couple of times. We've also taken him on two cruises to the Bahamas and Mexico. This summer we flew to Alaska and took him. His travels frequently come up during conversations at the dinner table and other times. He enjoys telling classmates about where he's been and what he's seen, done and experienced. These trips are invaluable in that they increase the childs knowledge of the world around them. We just got back from a trip to the mountains in Tennessee last week and he's talking about where are we going next? I can't wait till he gets his license and then I told him he's going to do all the driving!