my tips, for what they are worth, I have avoided the summer months my last few trips, but these should still apply
1) Rope drop your park of the day. Plan a sit down lunch.
2) Take a mid day break. I stopped calling it a pool break cause really the purpose was to get out of the sun and into the AC
3) Take extra clothes. Esp. Socks. Much nicer to put on dry non sweaty clothes to go back to the park
4) Go back after your break! Check park hours and take advantage of late night hours.
5) know your group. My family has a few people that do not like waiting in long lines, but as long as the line moves, they are ok. If you need to ride a slow loading ride, do it in the first few hours of your day
6) Nap/Cool spots MK- Hall of Presidents, Carousel of Progress, Philharmagic. Epcot- America- enjoy the voices of Liberty and the show! France,Canada and China for the movies. RIP Ellen. DHS- not sure what is still open tbh...AK- the shows.
7) Have a great trip!