I love doing this too. For 16x20 prints I have this nice book that is meant for water color artists. I put photo corners on each page for a print, and insert one on each page. Works great, looks great, and the prints are perfectly protected.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh