Scanning them is an interesting thought! Many of the envelopes are decorated, too (my DH is an artist so he personalizes all store-bought items; he even makes all the xmas gift tags, so I've got a bunch of those saved up over the years, too). I could scan for the scrapbook, and then keep the originals organized in a box or something. I'm going to think about this for a bit, I think it might work.
Yes, the multiple-scans per page idea definitely makes sense, I've got a whole CD to take up to Walgreens today with photos that I've resized/cropped/edited in some way - I used PhotoShop to put 2-4 pics on each 4x6 layout; it's cheaper this way, too- instead of paying for each individual print to be reduced or enlarged, I'll pay for the 24-photo deal and end up with maybe 50-60 photos