I'm closer to Cyl but without as much stuff (or the nice boxes).
My shared bank holds collectibles (first bag). As each alt goes through them and takes what she can use, she moves the gray stuff up toward the top. After all alts have been through them, the alt who originally dumped the stuff in gets to put the leftovers on the broker.
Second box holds L&L stuff, same deal.
Third box holds treasured items that were too good to vendor or transmute immediately. After everyone has had a chance to pick over them, they get 'muted.
Fourth box holds advanced pages. When an alt gets high enough in that trade to use it (or to see that it's redundant), she puts any leftovers on the broker.
Fifth box, spell books.
Sixth box, shared (mostly holiday) trade goods.
Seventh box, stuff my alts made for each other (so sweet!).
The remaining space is mostly spillover from 3-5, because I haven't gotten around to getting bigger boxes.
They're also a dumping ground for when I'm in a hurry, but I try to keep them fairly sorted.