What to Hang Above the Bed
As with any large wall, the wall behind your bed is one of the biggest challenges to decorate, yet one of the most important. It is the focal point of the room...or at least part of it! In most bedrooms, the bed and the linen are the unmistakable focal point. And as you look at the bed, your eyes will naturally travel UP...which makes above the bed, also a focal point.
What you decide to hang over your bed will depend on many things. There are however, a few general guidelines that can help you decide.
Large Art
The important word here is "large". If you have the vertical space, large is what will get you the biggest impact.

That's not to say that a smaller art piece won't work, but if you want impact, you have to go big!
A Set of Frames
This solution is a classic. In my opinion, all the frames should be the same. When placed within 2 to 3 inches from each other, it gives the affect of a single large art. You can frame just about anything. The important thing is that they all relate.
OK, here goes...I'm going to say it! I know a lot of my clients will totally disagree, but... if you're hanging a set of frames over the bed in the master bedroom, don't put your kid's pictures in the frames. Your children's pictures can go elsewhere in the house. Your master is just for you and your partner.
Of course it's not always necessary to create a "square" configuration with the frames. You can also create a gallery to cover most of the wall. But again, they should be spaced 2-3" apart and must all relate to each other either in color, shape or subject.