Since before Christmas will probably be less crowded than the 28, I would recommend switching your US and IOA days around. First thing in the morning at US: go to Transformers and then the Mummy. IOA: do not fall into the trap of going to Harry Potter first thing in the morning. I would do Hulk Spiderman and Dr Doom first, and the water rides if you like those. Then do Harry Potter later in the PM. Have a great time! Will be in Orlando area between Dec 30 and January 5