Ha ha - we spent our 10th anniversary at WDW - WITH our kids. Some day it would be nice to go back without the kids.
As for non-WDW ideas...I like the sound of a beach somewhere. More relaxing, kwim? Europe was awesome, but for most folks - rather go, go go.
I would like to go back to Switzerland for an anniversary at some point. I always said I wanted to honeymoon there but it didn't work out then. That said, we were in Switzerland for a couple of days in March and unfortunately our only sightseeing day was coated in fog. Lucerne wasn't quite as magical when you can't see any of the mountains.