I have a postcard collection. 

The postcards are either cards I've purchased or been given and they just sit in a box. I've got maps and business cards that I've collected over the years and they just sit in a box.

 During our packing/sorting/purging just before our move to Texas, I decided that these items were no longer going to remain hidden in a box in a storage unit, I was going to put them where I could see them.

We didn't get many souvenirs on our cross country road trip, but I couldn't resist grabbing a couple of items at the Grand Canyon gift shop. I wanted to page to mostly be the memorabilia, but added a small selfie to round out the design.

For memorabilia that doesn't fit so easily on a scrapbook page, I think these 12x12 envelope page protectors are a great option. This is where I would put bulky things like maps, booklets, pins, etc.