Actually a 2 bedroom deluxe will sleep 8 adults (2 in the king in the master, 2 on the pullout couch, 4 split between two double beds in the second bedroom). Yes, if you are traveling with couples that might be a weird sleeping arrangement or if your folks spend more time getting ready in front of a mirror you may run into bathroom problems, but if this is 8 low-maintenance folks I would absolutely recommend Wyndham Bonnet Creek. We have booked it twice, once at $159 per night and more recently at $135 per night (during spring break season). I looked harder for the second deal and found what I wanted on VRBO. If you figure finding something at $160 per night divided by 8 people makes the accommodations only $20 per person per night so I would definitely use this rationale to justify the expense of a couple of rental sedans. You can probably find those at a low price as well if you watch sales and book at the right time. Parking is free at Wyndham Bonnet Creek.
Another property of similar quality which would also put four adults to a room in two queens rather than two doubles is the Wyndham Lake Buena Vista (Disney Springs). We recently snagged it for $85 or so per night after figuring in the resort fee and parking charge (which you won't have the latter, but it was only $7) which would also come out to about $20 per person per night. The shuttles there are included in the resort fee, but you can easily walk across the pedestrian bridge to Disney Springs and ride the Disney buses to any WDW resort you'd like (meaning you would not have to connect at the TTC for MK if you would like to walk to and from the Contemporary).
The advantage of Wyndham Bonnet Creek is the kitchen - if you plan to prepare meals there I'd pick the condo style room and bite the bullet on renting cars. If you'll eat all your meals in the parks I'd pick a Disney Springs hotel with a low rate and shuttle service included.