Your itinerary looks good. Our kids are not at all interested in Sea World, so we planned two days at Universal/IOA. I think DHS and AK can both be done in one day by reading other TR's. We are doing a 1/2 day at AK and doing the Christmas Party at the village that evening. Hollywood Studios, we are doing during our extended stay, but we are going early afternoon for a big lunch and staying late for the Osbourne Light show and Fantasmic.
Have you thought about
MVMCP?? We are skipping this only because we had to buy an extra 2 day park tickets for our extended stay to get the Free Dining package. We have Magic Mickey hours one night until 11pm. Otherwise.. we would totally do the Christmas Party! That will give you entrance at 4pm until late and you can use the other ticket for Epcot.
Just some ideas.
I talked to our MAW Manager today about the rental car.. we have the same issue. He said our car is through National and so I booked our extended stay through them. I'm hoping they will just take our credit card and extend the car for the five days without us having to return it for a new car.
Things are coming together!! FOUR weeks!! Eeek.. Can't wait to see you guys at GKTW!