It also depends on the height/weight of your headboard in the room. Can you post pics of the wall with the headboard and the artwork?

If reading in bed I would not want my head to hit anything hanging on the wall. The last pic above things look good but seems like heads would hit it.

If the headboard isn't overpowering and a statement in itself, I'd go ahead and put lightweight art above... even though I don't live in earthquake country, I'd be nervous about anything heavy up there.

Agree with arcy, I wouldn't want to have anything so low as to be hitting my head on anything over the bed when sitting up in it.

So a photo of the bed would be great.

its also a matter of the thickness of whats getting hung. something slim to the wall gives a different feeling than thick.

but i'm another that doesnt like anything wood / glass /metal over my head in bed. (we have a set of painted and carved wood panels screwed to the wall as our headboard.)