I think my tall (45 in) 4 year old would like Mission Space, but I'm not sure if it will be too much for him. I would definitely do the easier version. We went to DL when he was almost 3 and he loved BTMRR, Splash Mtn, Space Mtn, and the Matterhorn. Does anyone have any experience of going on M:S with a 4 year old?