I don't really care for the look of colored beams.

If you are on a budget, I'd spend the money on a colorful throw for the end of the bed, some art and a larger lamp with a colored base.

Agreed. I think colored beams will take away from the room, not add to it.

Agree, don't paint the beams. But you could paint the ceiling between the beams. I think a very pale blue would be nice with that ethereal light coming in.

I used Sherwin Williams Sky High 6504 on my kitchen ceiling. You can see it at the top of this picture. Just a whisper of blue that I love.

Here's some painted ceilings with white beams:

Crisp Architects · More Info

Wm Ohs Hampton Classics · More Info

North Shore Pine Street · More Info

Painting the ceiling is so much nicer than this:

River Park House Plan · More Info

I'm not familiar with the brand of paint from B&O. But as along as it has good coverage, it won't get any wear so probably okay.

I see you mentioned sage. You could also do a very pale sage.

I wouldnt like the colored beams either, they will make the ceiling look lower. Put your money into new bedding and draperies, wall decor, and some accessories. Thats what the room really needs. The beams look nice the way they are.