I must agree with BVC23. The Poly is a great choice, but once you stay there it is very hard to stay anywhere else. We stayed there (lagoon view, concierge) in 2002 with our DS's (then 6 and 4). It was great for them. The volcano pool is fantastic with its zero entry end and great slide through the middle of the mountain. The beach is right there for the kids to play on. We actually skipped going to Universal for a day just to stay at the resort and relax. Also you can't beat the location with both the MK and Epcot monorail within walking distance of our room. The concierge was great for us. We ate breakfast there every morning and the kids loved being able to go to the lounge on their own to get a snack or drink. Made them feel very grown up. We also used the concierge for light dinners by the pool. We would eat a big lunch late in the afternoon at the parks and then come back to the resort, get in our suits, pick up some snacks and drinks at the lounge and sit and watch the kids play in the water. It was wonderful. You will love it.
Unfortunately for us we will be staying at the CR Tower Clubwhen we go this May. DW got a great rate there that was too good to pass up. I knnow we should try other resorts but like BCV23 said, once you stay there it is hard to stay anywhere else.