You certainly can do that at Disney. Not sure about Seaworld, we always go for park opening but since Seaworld is owned by the same company who own US/IOA and Busch Gardens I would think you would be able to.
Are you really sure about that Florence, I'm 99% sure it's free at SW and US etc, but I thought Disney were happy to take your money right to the bitter end!
Ian
Last year we went to AK at about 2.40pm and there were no car park attendants on duty. I have also (mistakenly, we were lost!) arrived at the Epcot car parks at 3pm to find them unmanned.
Wont have to worry this year as we are upgrading to APs and get free parking! Hooray!
You're alot luckier than us Allie. we've never escaped the parking pass cost, not at Disney anyway. This year, because we've got Fun in the sun tickets, we'll probably go to parks for less time each day, so may go later in the day for the first time. I hope we find them unmanned...
Ian