People often include a pack wrapper when they're selling sets, but it seems to me that they don't really know what to do with them. What I mean is, I'll often get the pack wrapper either lazily folded to an arbitrary size and either placed on top of the set pile, or put in a separate oversized protector. I'm not suggesting that there is a right or wrong way to do it, but it just seems that people aren't sure what to do with the pack wrappers even if they are sure that they want one to include with their sets.
I've developed a method for collecting and storing pack wrappers that I'd like to share in case you're interested and just haven't thought of it--not that it's some kind of genius idea or anything. I just take an extra card and insert it into the pack to use as a mold for folding the edges around. Then you have a perfectly-sized card that can fit into binder pages or penny sleeves.
Card packs often include a bunch of "throw-away" cards like promo or game cards that serve perfectly in this role. When making the folds, I fold the top edges first, and then the side edges with the bar code exposed. In terms of centering, I try to leave an equal amount of space from the edge of the lettering, which sometimes requires multiple attempts.
I got thrown off a bit when I started collecting foil packs, but I eventually came up with a similar concept. In this case, I pick one side to fold that would result in the best centering, and then fold the top and bottom. You have to put the pack into something quick because the folds don't hold well at first. Folding two sides would be difficult, so you just "gotta" kind of choose a side.
This 30th Anniversary pack example I chose probably wasn't the best because the picture is too large to be contained within a single card size. Most foil packs don't have this problem, but in this case, I was left the decision to cut off either the brand logo at the top or the banner at the bottom.
Like I said, this is just one way to do it. The idea for a post came to mind when I received 2 complete 88-card variation sets of OS3 in the mail yesterday. They arrived in some fancy 100-ct. plastic set cases that I had never seen before (remember the hinged plastic snap cases?). The pack wrappers were kind of folded enough to smash into the case. So I thought, it's probably not that people don't care; they probably just don't know.