We went last year on Saturday the 17th, figuring the same as all of you that it would be a better bet than Disney parks on Saturday near Xmas. We had already seen the big shows so planned to see just Clyde and Seymour, plus we don't do thrill rides. We arrived at opening and hit the dolphins and stingrays (spent a long time and much $$$ feeding them), Arctic area including Wild Arctic ride, and sharks. Minimal crowds. Very happy. Grabbed a bite at Voyager's pizza when it was starting to get a little crazy... did the Clyde and Seymour show and the otters and sea lions area. Then progressively more crowded till we felt a little battered and left at about 3:00. We are pretty crowd-allergic so if you have some tolerance for bumping up against other people you might have been OK for even longer... I hate crowded pathways worse than I hate waiting in line even!
Hey, we're probably going to do the same thing this year, so we'll be part of the throng on the 16th! See you there!