Hi, we went when my daughter was 3-1/2, and then we went just in May, and my daughter was 6-1/2 and my son 2-1/2, and I was worried about my little guy, but he LOVED it, was amazing.
If you got a great deal, heck, the 3 year old would love it, and probably the 1 year old if you decided too, but probably not that great...it is so expensive!!!
Maybe you could go the hotels that have waterparks. They have the 0-depth water. Go to one that is inside and outside maybe? They seem to be having alot of good deals - just google it? We are going to Shipshewana next month (they have an inside one) - so the kids will have fun, but you could also go shopping, and they have great restaurants.
Any place that you pick I am sure they will have smiles on their faces!
Also, if you get lucky, like we did a few times, is we would go to places that we could put the monitor in their room, and we sat basically right outside their room by a fireplace with some wine, so the kids were sleeping in their room, but we were right there - we could see the door. We just called and asked the front desk if they had a room by the "main room" so to speak? Just a thought!!!!