only problem we had were older larger kids running over younger toddlers there as it is too small for number of kids usingThe Boneyard in AK Dinoland is great. it's well contained. There's a great little play area that's perfect for littles at Splash Mountain. It's on the right as you are heading toward the restrooms that are tucked back in there. The standby queue for Dumbo is an indoor play area.
There are some great little splash pad areas scattered around epcot
I really miss Honey I Shrunk the Kids at HS. Loved to play hide-and-seek with my kids there.