Oz and Xander, both being native Southern Californians, are so used to going to Disneyland, that, when they begin dating, it's one of the first places they go.
There's the Tiki Tiki Room, and the Haunted Mansion, and they sneak a few kisses on Tom Sawyer's Island before some kids find them and go "Eewww", but they're really fond of Pirates Of The Caribbean.
Well, after Star Tours, 'cause, c'mon. Star Wars.
So they go every year, together, and when Xander finally decides to propose, he does it on Pirates, right when the skull and crossbones remind them of tales.
This Angel/Buffy the Vampire Slayer story was written by Kate Bolin. If you liked it, there's plenty more at http://www.dymphna.net/fanfic/. And you can feedback her at dymphna@dymphna.net.