Rooms at Poly and CR sleep five and are larger than rooms other deluxes except GF (IIRC). CR garden wing is cheaper than playing for the tower ($400 or less per night for the time of year I've been looking into). Poly is more expensive than CR garden wing. Other deluxes such as BC, YC, BWI and GF sleep five adults, thought GF would be way over your price range (unless you get a room with a 25% discount)...and the rest are smaller than Poly or CR. You would be very snug, but depending on your touring style, it might not matter. You'd get one bathroom, however, which might make a different.
AoA family suites sleep up to 6 adults, have two bathrooms, a 'kitchenette' (a microwave in addition to the small fridge that all WDW rooms have) and are under $400 per night. You could also get two moderate rooms for less than $500 per night (especially if you get one during a discount period, which those days in December usually fall into). Some value resorts also have suites (AoA is a value, but I personally feel the family suites are a step above most value rooms).
Edited to add: You can also look into renting points for a DVC resort, but I'm not sure if 1 BRs sleep five adults (and a two bedroom unit might be out of your range, even renting points...not sure).