At that age, I'd say just go on your family vacation and have fun. Kids are learning all the time, and being well travelled is an education as well (learning how to behave on a plane, what seeing the cultures in Epcot, trying new foods, exploring things). Keeping a journal is a fun thing to do, if they're so inclined (my oldest did that when we went to Hawaii when he was 7, and I still have it, but their Montessori school encouraged family vacations, and some kids even missed close to a month to do international travel to visit family - the school was very encouraging of it).
It gets harder when they're older, and a nightmare in high school (we've had to due to family things; had to bring text books even as it was right before finals!).
Enjoy now that he's young!