I had a few designs back in the day that I really liked....probably not what you are looking for but it might give you a few ideas.
Back when there were such things as player-run towns (On Origin at least) we had several buildings...auction house, library, town hall/jail, tavern etc.
Unfortunately I lost all but a few, this is the library (No images of the inside) And a bit small
My auction house (Designed after the original Europa Auction House if anyone remembers that
)
Then I moved my auction house to Zento to be closer to a moongate
This, by far, was my favorite, I actually re-did this design a few times and wish I had an 18x18 to do it again...no interior images again but it was REALLY cool lol.
I know that with the new craftables, things can be done now that couldn't back then, but I still think that if you don't want or need extra floors, you can do some pretty amazing things with what you have.