The bar

That's quite a concept you've got going there, although that staircase arch going though the middle of the room might need some hand rails. Imagine a drunk person trying to get up those, quite the comedic picture.

Over all, only 2 areas really stand out as needing a bit more work. The wood on the counter appears to be rather stretched and in need of either gloss or bump mapping, the latter could just be due to the lighting. The other bit would be at the back of the room, the endless grey color wont carry much contrast, so I would try another color back there to add some life to the scene.

None the less, this is a great render and good luck on your next project!