I would paint the walls, ceilings and trim in the same color - especially in the short guest room. I you introduce another shade of white it will break up the walls too much. However, I would vary the sheen - a flat finish on the ceilings and walls and a satin finish on the trim. The difference in sheet between the molding and walls will help it to stand out even though the color will be the same.

Would you also suggest walls, ceilings and trim the same color in this room? BM Cotton Balls is the white I was planning on painting there walls. Thank you so much for your advice!!

What a cozy room! I actually like the way the white trim frames the window so I'm going to back-track and suggest painting the ceiling and trim a crisp white. Benjamin Moore has a color called Chantilly Lace which is very nice. Again, I would keep the ceiling a flat sheen to minimize glare and paint the trim in a satin finish. You might also want to consider swapping out the lampshades to help coordinate the the bedding and stand out against the lighter walls.