The first year we went to Disney my kids were 8 and 3.5 yrs and we stayed onsite. It was great, the kids loved it. The next year we went with friends and cousins so we rented a large house with it's own game room, splash pool, resort pool etc. at Paradise Palms Resort, which was fantastic. We're heading back in November and I gave them the choice as to where they wanted to stay, they both chose off-site because they loved having their own pool and space to run around so we're going to try Windsor Hills. Either way, both experiences have been magical. You can't go wrong no matter which way you choose.
Just got back from Windsor Hills...you will love it! Everything about it is perfect! It's where we will be staying the next time we go.