Is your party a total of 11 with 5 adults and 6 children? If yes, that sounds like 3 cabins.
September should be off-peak. You will probably save money by booking the Land/Sea separately. You can do a search on my user name, and you will find a thread I posted about some of the hassles concerning doing the Land/Sea together. It gives you alot less flexability. (You can look into the Passporter series,
www.passporter.com. These books are full of tips about
Disney vacations and the cruise book recommends booking the package separately) For instance;
* You will have to do Disney World first, cruise second.
* You are limited to the resorts that their program uses (No Animal Kingdom Lodge even if you want it)
* You will be unable to reserve rooms on the Land portion. You just get what Disney gives you. (I'm doing a Land/Sea at the Poly, and I can only get Lagoon view if they just happen to be available, despite my booking 14 months in advance)
To be fair, the Land/Sea together gives you two solid advantages. First, if you are flying in, you will have the option of booking transfers. They are actually $39 per adult, and give you transportation from the airport to the hotel, from the hotel to the ship, and from the ship to the airport. An excellent value for the price. There may be a charge for the children depending on how old they are. I booked transfers for my neices who are under two and there was no charge.
Second advantage is the one stop check in. When you check in at the resort they also put your cruise paper work in order. This basically leaves you with the ability to just about walk onto the ship when you arrive at the terminal.
As far as the deluxe resorts, the Contemporary and the Polynesian are both on the Mono-Rail. This would be important if you want to avoid a car rental and thus plan to stay on property for your entire stay.
I hear great things about the Wilderness Lodge, and understand they have a fantastic restaurant for the children (Whispering Canyon Cafe).
If I was doing this all over again, I would book the previous mentioned Animal Kingdom Lodge. You can get rooms that face the veldt. I think the kids would go crazy to wake up to Zebras and Giraffes in their back yard.
I'm doing category 6. Rooms 6550, 6552, and 6554 (two of these connect). I will post a review of my trip when I get back (my cruise is 5/2). Maybe that review will help with your decision. You can't book for 9/05 yet anyway. I believe that 14-15 months out is the earliest they will make reservations. Hope this helps.