Our girls (2 & 6) will eventually be sharing a room once we figure out what sleeping arrangements will work best for us/them in there (in terms of using our space well and having the kids and co-sleeping mama happy).
Dh kinda only says bunk beds (which I dislike mainly because I'm the one who has to change sheets, sometimes very often with young kids and wet beds).
I'm considering just finding a full size bed for them to share, and keeping dd1's single in there (which has lots of storage under the bed) as a daybed type thing (aka dumping ground for toys - but at least I could just shove everything there and off the floor too).
OR just go ahead and get another single bed of some kind (would have to be storage smart, because we'd have to eliminate some other furniture to fit this, I suspect. And yes would probably have to do so with the full too, I guess).
There are currently 3 tall bookshelves, the shorter open shelf for clothes, one dresser, desk for dd1, and then trunk and rolling small table for playmobil in the kiddo's room. There's one smallish closet too.
Other ideas that are interesting for bed/room sharing that you've come up with welcome too. The kids currently have an open shelf for most of their clothes that they share together (and one small dresser they share for pi's and leotards).