Do you have enough storage for all of your supplies behind the bar? I might put a bar cart on one side of the bar with framed art above it, and a club chair in the corner on the other side (if you can slide the couch down a bit to make some room). Other option would be to flank the bar with club chairs. I would add open shelving in wood or glass behind the bar (where the painting is). I actually wouldn't do wallpaper or an accent wall behind the bar because you have the bulkhead on that wall. I would instead paint the walls and the bulkhead the same color. I like dark masculie blues or greens for a bar area, depending on how much light you have in the basement.

Definitely shelving for bottles and glasses. Why don't you go to a thrift store or an antique store and find some old posters or beer signs or neon clocks with advertising to put behind the bar. I think it would be more "eclectic" than the piece you have up there now. You might want to consider a "theme" to building your purchases around. I would add bar stools too. Do you need a small refrigerator?