Y is for: Your very own roller coaster
A newish (2009) and underplayed gem at Epcot is the Sum of All Thrills in Innoventions East.
At this attraction you get to design your very own roller coaster from beginning to end, and then you get to virtually ride it! It's SO much fun, and for something I'd barely even heard about, way cooler than I expected.
The enclosed capsules for virtual riding can be a bit intimidating to some (like my son), but even the claustrophobic can participate---my daughter and I didn't peek while he designed, and then we girls rode his creation at our own risk.
When the attendant looked at our design card and asked, "You're going upside down three times?" I could only reply, "Apparently so."
Disney World Trivia
Which of Disney World's four major roller coasters is the shortest in duration?