I think one day is my personal limit, actually. I will be there with DS1 who is 11 and DS2 who is 9. DS2 is currently 139 cm tall... I think that means if he grows 1cm he can go on any ride he likes. DS1 and I are both 160cm. We really like Legoland but they are growing out of it now.
If you had just one day there what would you make sure you did?