My DW and I always let our kids pick one new ornament apiece to decorate our tree with. Over the years, it's become really nostalgic to re-live the trips through the ornaments.

I also like to get a really nice Mickey pen each trip. I usually find one in Downtown Disney somewhere.

I also like adding one particular T-shirt: the one that has the four park logos across the chest with a Mickey in the middle. Right now, I have a navy blue one, a red one, and a green one. If I see a white one next trip, I'm getting it!!!!