It's all about how much you can spend for lodging, really.. We have stayed at Holiday Inn Family Suites and it was WONDERFUL!!! They had a main bedroom with either a king or queen ( I can't remember ) and they had a separate bedroom for the kids with bunkbeds ( which my kids LOVED ) and they had their own Nintendo games, , etc. in their room. They had free train rides for the kids around the complex, special check-in for the kids, and lots of other kid- oriented activities, no to mention the wonderful pool.They gave free shuttle service to the parks , and very minimal wait time between shuttles. I thought the price was very reasonable for all that we got, plus kids eat free.
On the other hand, if you can afford it, and you really want to stay on-site, the Boardwalk VILLAS are fantastic. They have 1 and 2 bedroom villas. We have stayed in the 1 bedroom villas and there is the main bedroom with a king bed, and a queen size sofa sleeper. They are very roomy and they have a washer and dryer in the suite which really comes in handy, not to mention that you have 2 FULL bathrooms, one with a large whirlpool tub, and the other with a large walk-in shower.
I have also read about the BEACH CLUB'S new Villas. The set up sounds very similar to the ones at Boardwalk, and the price is essentially the same.
Both the Boardwalk and the Beach Club have lots of activities for kids, and they both have AWESOME pools-----always a plus for kids.
Anyway, hope this helps.....Good Luck ! Planning is half the fun, don't you think?!