tough question. guess it depends what kind of pass/passes you buy. (we have BGW plat. passes, so we've been to SW and AQ multiple times. But, sadly, never sprung--yet--for our gang to do DC. Come on, who doesn't want to swim with the dolphins?!?)
DC, as i guess you know, is much more expensive. It varies...and I think you get a choice of a seven-day "extra" pass for one of the other local parks. So, if you do DC you're covered for whatever else. If $$$ is an issue, a two-day ticket for SW and AQ, would be cheaper than DC admission.
If money is no object, in Feb., I would do DC and SW.
We've had three of our children as four-year olds at SW and they LOVED it. Only real issue was trying to "pet" dolphins at the feeding time. Their arms were not long enough to reach.
(Bring spare clothes or prepare to purchase a new SW wardrobe. They will get wet petting the sting rays, especially. Two of our kids practically tried to get in! Add in the fish and shrimp smell...uck!)
That having been said, are you doing other water parks, weather permitting? We also loved AQ. It is compact and well-done. Depending on how adventurous your child is, AQ has the best smaller child play areas. Our son 4.5 at Christmas was underwhelmed with one area previously loved, but he is a wild man! He was a little disappointed cuz he was too short for a few of the grown up slides.
In short and, no help, you can't go wrong with any of the parks, imho.
