Whenever you buy a souvenir at any location or on any vacation, I think it helps to think about what you will actually get use out of. Disney has TONS of merch (of course) and it's easy to get sucked into buying something that may end up sitting in a closet for months. I agree about skipping things like Vinylmation (has no interest for me anyway), and I think the PP's ideas about creating a tradition with a new figurine or mug each time is great.
Things I've bought or seen that I think have high use potential:
-Mugs (if you drink coffee/tea regularly)
-Tshirts and graphic tees - just be sure it's a design you really like and see yourself wanting to wear!
-Magnets
-Antenna toppers/car decals
-Jewelry
-Christmas ornaments
Things that just say "Disney":
-Mouse ears
-Antenna toppers
Also, consider the gift shops in the World Showcase at Epcot. As a PP mentioned, Japan has the pick-a-pearl option. Their gift shop is HUGE and has nice Japanese dishes, art, etc. France also has some really nice things. The things you get there may not be explicitly Disney, but they will remind you of your trip and all the fun memories when you use them
Oh, and you can get free buttons at the parks that say things like "I'm Celebrating!", "Happy Anniversary!", etc. I'm a passholder, and I get one of these every time I visit. I then write the date and occasion or who I was with on the button in sharpie. I used to have my collection at my cubicle, but I recently quit my job - now I need to get a corkboard to display them at home! The best thing is that they are FREE
