Cut out shapes the size of your furniture to scale and move them around on a same drawing of the room. That is what I do.

Thanks Maine! I have done so many layouts on graph paper my head is spinning. Was hoping someone might have a fresh take. :)

I agree with mainenell-- you've probably got more than just the bed to consider fitting within the space. Scale drawings including furniture will help you figure it out.
I do think it's preferable for both sides of the bed to have easy access to the bathroom though-- that would weigh in favor of placing the bed under the large window on the long wall. If you had space, I'd suggest putting the bed on the short wall the bedroom door swings toward, but it looks like that might not leave room for bedside tables?

Thanks TB! I agree with both sides of bed having access to bathroom. Is there anything worse than crawling over someone at 3:00 am to get to the bathroom? ;) You are right, putting the bed on the short wall leaves no room for nightstands. I typically don't like beds in front of a window, but I'm not sure if I have a choice. Maybe if I use an open type headboard and some drapes - similar to this picture.