I like (along with a few more conventional souvenirs) the sort of things that everyone remembers and has pass through their hands, but few people have once they get home (and I'm not talking about cash!). Read on ...
Back in January, we took our little boy to Walt Disney World for the first time. He had turned two in August. He won't remember much from the trip, if anything. I got the idea to make a shadow box for him, and made it my business to collect items for inclusion. I have a Key to the World card, a Walt Disney World napkin, guide maps for all four parks, a price tag from a toy dinosaur we bought for him, a wristband from Extra Magic Hours, the newsletter from the resort (All Star Sports), a bumper sticker, an unused FastPass, a Times Guide for the time we were there, and a couple of photos of him from the trip. I put this and some other things I can't think of at the moment into a folder and have it put away until I get the chance to buy a shadow box large enough to hold everything.
I personally love baseball caps (I'm very particular about which ones I like, though -- I'm on my second one in 10 years), and a pin or two from each trip. I just buy the pins I really like -- I'm a graphic artist, and I enjoy the pins as great examples of what amounts to logo design.
I agree about photos. I'm not much of a snapshot guy, though ... we have very large framed photos of park icons hanging in our house. We have 18x24-inch photos of the gateway from the hub looking into Tomorrowland at dusk and another of the rocky spires of Big Thunder Mountain Railroad hanging in our living room. Just this very day I framed a photo we took on our most recent trip -- an HDR shot of Cinderella Castle late at night, bathed in vivid blue, pink and red light, with absolutely no guests in the shot! I'll probably be hanging that one tomorrow.
Another thing I really like are the reproductions of attraction posters sold at the Art of Disney. I have several. The Walt Disney World Monorail System poster is hanging in our dining room. In our bedroom, we have The Haunted Mansion poster on one wall and Tomorrowland on another. I also have posters for Big Thunder Mountain, Pirates of the Caribbean, and the Walt Disney World Railroad still their tubes, awaiting the day when I can afford to have them framed. All the posters are the preprinted ones they used to sell, except for the railroad poster, which is one of the print-on-demand posters. There are still a few others I want as well ... more so than most things, having these is really like having pieces of the park at home, because they're actually on display here and in the parks!
SSB