Re: What color would you paint...
Light blue (i could do a lot with a 'sky' blue and maybe paint clouds on the walls) or green are probably my top favorites right now. Yellow or teal could be ok too.
I don't personally like grey - it screams industrial look to me not bedroom. While I don't assign gender to color, ds would not like a purple room. It would be a girl room to him (he has 2 older sisters he likes pinks and purples but that stuff is typically his sisters hand me down stuff so to him it is girly stuff (that he has no issue playing with)). Tan could work - most of our house is tan - I usually like more color in a bedroom but it is neutral and does fit the bill.
Lots to think about - thanks for the ideas. We're still debating whether we really want to paint the room now or wait a year and see if they want their own rooms again by then and paint then.