With a group of that size, and cost a concern, I recommend staying offsite. You can rent gorgeous 2 & 3 bdrm townhouses and condos directly from the owners for less than the cost of 2 rooms at a value. Yes, you would have to have a vehicle, and pay for parking, but it will STILL be cheaper and much more comfortable. Website for that is
www.vrbo.com.
You can also bid on ready, set, go auctions at skyauction. You can choose from 1, 2 or 3 bdrm units, and the cost for all is the same (when you win an auction, you can choose from whatever size unit is available for your time frame). Website for that is
www.skyauction.com. Many of us have used skyauction successfully (I've used it 3 times, each time for a 2bdrm condo. Most I've paid is $266. including all fees fot he the entire week!)
You could check out renting timeshares from the owners at
www.redweek.com. Bonnet Creek, although not a Disney resort, is adjacent to the Caribbean Beach Resort, and very close to OKW. The Marriot resorts (Marriot Grand Vista and Horizon's by Marriot) get fabulous reviews from families.
If this is your first trip to WDW, don't get sucked in to thinking that you MUST stay onsite to experience "the magic". There is no magic in stressing over how much the accomodations cost! We have had 3 trips, none onsite, and they have all been "magical" in their own way. While at some point I will most likely give onsite a shot for a few days (that's all we could handle with 4 of us in one room!), if I had insisted on onsite for our first trip we could never have afforded to make 2 more trips! When we saw how inexpensively it could be done it made it easier to budget for the other trips. Personally, I would love to be at the Poly too, but I am not willing to pay $400. (or even $250) for the priviledge. What I would spend on hotel alone would pay for our entire trip offsite!
Have a great holiday, whatever you decide to do.