We are also a family of 7 and have changed plans for our August trip. Trying to be budget conscious makes my head spin at times! My sister is joining us for this trip so that is another change. Our original plan was 2 rooms at POP for free dining. We then switched to 3 rooms since we didn't want to make sis or 15yo ds share a bed. Then we switched to a family suite at ASMu and another regular room. This was a little more expensive but gave us a kitchenette and a seating area which are both important to us. This week, just shy of our 45 day mark, I was poking around the rent/trade board and found someone who was renting points for $8 per point. At this rate I was able to book a 2 bedrrom villa and add the dining plan and 10 day tix and it was only $150 more. This increas was actually on the tix themselves since we would have to buy 2 10 day tix rather than upgrading from a 2 day. It also means we will not have 5 2 day tix leftover. Definately a good tradeoff imo.
I hope our story helps you. If you are comfortable with 2 rooms at a value, that is probably still the cheapest way to go. However, if having a kitchen, sitting room and laundry facilities are important to you as they are to me, you may decide a villa is actually a better deal.