A 2BR or 2 studios are about your only options. I would urge you to think about your length of stay etc, as far as which to rent. If you like the option of a full kitchen and washer/dryer, then the 2BR is the way to go, especially if your stay is a longer one The washer/dryer affords you the ability to pack less since you have the ability to do laundry.
However, if privacy is an issue, then perhaps the 2 studios would be a better choice, as you can get physically "away" from your travel companions more effectively than you could in a 2BR.
I have travelled with a group of 5 adults...2 couples and 1 single...and stayed in a 2BR, with the 1 couple in each bedroom and the single on the couch. It worked fine, since we all pretty much get along and like each other. However, If I were to travel with my SIL and her 2 children, I would opt for 2 studios, as her children are not well-behaved, she is annoying and I would feel like I had no "escape" in a 2BR.
Just another perspective, but an important one to think about. I know Disney touts family, an Magical Gatherings, and shows all the videos of happy extended families romping together through the parks, but the reality of the situation is that after a while, even the closest of families can get on each other's nerves under the right conditions.