ICE! at Gaylord Palms might be an idea. Plan to spend the whole day.....have breakfast at the Shrek Feast (a character meal at Villa de Flora featuring Shrek, Puss in Boots, and Fiona....the food is phenomenal and the character interaction is really fun), tour the ice sculptures in the ICE! exhibit and slide down the ice slides, decorate cookies with Gingy the Gingerbread Man, visit the turtles and alligators (which are all overseen by Gatorland) in the atrium, and just enjoy some time taking in the free holiday entertainment and gorgeous decorations.
Gatorland is also a low-cost, fun and relaxing attraction. They have a small train that you and your little ones can enjoy for a ride around the park. There's also a petting zoo, some short shows, lots of gators/reptiles/birds (some of which you can feed) and a great little splash park if its warm enough.
Or.....what about the Orlando Eye attractions? You could ride the Eye, visit the Sea Life Aquarium, and then tour through Madame Tussaud's Wax Museum. Combo tickets are $39 per adult for all 3 attractions.
