Another option if you want to stay offsite is to rent a 3 or 4 bedroom home/condo... You can save a BUNCH... we have done both... personally I prefer onsite because of the Disney atmosphere and transportation system... BUT the large three bedroom condo we rented in 2002 was exceptionally nice and at that time only cost us $600.00 for a week... nice to have a kitchen and laundry but did not care for the drive to/from the parks... even though it was only 3 miles from one on the entrances... It took a while to sort of get comfortable coming and going... Another thing you will find is once you get to a park you are not likely to run back to the condo/home for a nap... you pretty much stay for the duration.... So that may also be a factor you need to consider... the ages of your party and what everyone desires are.
Have a Great Trip,
Mark