I think it really depends on how old your kids are and if you are planning on spending alot of time at your resort. We stayed at POR for our first trip with kids (then 7, 5 & 4) and loved it. We were not in the room much and the kids were little. Our second trip in Dec. 2002 the kids were a little older (9, 7, & 6) and we decided to upgrade to the Polynesian because I got a great AP Rate (and it was always a dream of mine to stay there).
Our next trip will be this Nov. The kids will be (10, 8 & 7) and we will welcome the extra space of the rooms at the Polynesian. Since our APs are already paid for from our last trip and I booked the room at the Come Back rate, we decided to try concierge (probably the only time we will ever be able to afford this). Since it is our third trip we are planning on spending more relaxing time at the resort and less running in the parks this trip.
So, I would say if your kids are young and you will basically be using your room to sleep, stay with POR. Otherwise, I have been spoiled and if you can swing it go for the deluxe.