We prefer full or even partial books, but we have flat covers, also. I used nylon thread ("fishing line") to stitch these covers to foamcore board, so the covers didn't get damaged.

The rest of the flat covers go into the binders (in 6 pocket pages) with chips, postcards and other paper...

Feature and printed stick matches are open so you can see the matches, in a display box that's got the batting/fluff stuff in it. The box is displayed in one of the cases in the dining room.