We like to go at the park's opening & do utilize the early extra magic hrs, just go early enough to get up near the rope & enjoy a nice chat with other visitors or get some tips from CMs. Plan to do the most popular rides first & make that all important dash. I would say have a plan on how to do each park & be flexible enough to take a golden opportunity when you see one.
I will say we try to avoid MK on Saturdays, prefering AK for that day. We do get Park Hoppers, as the OP noted, if one park seems too crowded there's alternatives
we use UG & DIS mostly-
We do tend to go at the less busy times, but we have always been able to make ADRs for an early or late lunch, the morning of. Even for Boma we were able to do 5 pm ADRs that morning. We like to do big lunches & lighter dinners
have a wonderful trip!
Jean