I dont know about getting there from the catskills, but dutch wonderland in lancaster pennsylvania is a great place for families. it is an amusment park for kids with BIG rides but not SCARY rides so kids of all ages have a lot of fun there. it has a mini water park area as well. dutch wonderland is also very close to Hershey park. there is a great hotel near by called willow valley/double tree. (it has 2 buildings – the original and the new one which is partnered with hilton) the hotel has a really nice kiddy pool and GORGEOUS grounds – lake and all!
hope this is helpful! 🙂