If you're going with a mid-century look, get a bed/headboard with clean lines. You could go with a simple rectangular shape or possibly a channel-tufted look in a soft velvet. As for colors, I'm a big fan of dusty gray-blues for the master: soft enough to feel relaxed, and not overly feminine. Will work nicely with the black accents.

It's difficult to choose, that's why you're having a hard time! :) Going through the same thing myself. Sabrina's advice is sound. I like the contrast of a black bed against a white wall. Have you collected inspo pictures? That could give you an idea of the look that appeals to you most. Notice the repartition of colours in the rooms you like most. How much dark, how much light, vertical surface vs horizontal ones.... Might help you hone in on your choice. And remember, there's no "one perfect way" to do it. I'm sure many options would be suitable and offer you a beautifully done room that meets your aesthetic and functional needs. Good luck!

Forgot to say: test out your black bed idea if you can. Get some black poster board from the dollar store or an inexpensive sheet and tape it (try to approximate the headboard size on your wall) with painter's tape to see the effect in your room. Give it a couple of days to see if you like the effect. You might appreciate the contrast or you might find it "sucks" the light out of the room or you might not be bothered by it one way or another.