On her first WDW trip, DD was 6. Before we left home, we found a Minnie Mouse toy that was truly a life saver. She was connected with elastic so you could move and shape her head, arms, and legs but everything stayed attached. It came from like the dollar store and was small enough to go easily in the park bag. She never got tired of playing with it the whole trip!
Moral of the story -- when seeking to entertain little ones, don't underestimate the power of the cheap toy!
We also play the Character Alphabet game, people watch, I Spy, tell jokes, share our favorite part of the day, talk about what to do tomorrow, etc. The kids are older now (DS17 and DD15), so for this trip, they will probably be wanting electronic entertainment but I'm thinking that at least one or two days/nights we will go device free so we can have family time. (I have to say that DH is as bad or worse than the kids when it comes to his gadgets so I might have a mutiny on my hands!)