Warmth would go toward red, coral and yellow. Have you considered wallpaper?

Sorry, I don't have suggestions for a specific color, but I'm thinking that a dark green or charcoal could potentially darken it too much. I think a neutral color palette could work well with your vanity top and cabinet color.

Bryant Bath - Transitional - Bathroom - Seattle - by Jackson Design Build | Houzz

I would love wallpaper but, finding something to work with the granite pattern is hard for me. And, maybe instead of warmth, I should have said that I want it to have more personality. I want the wall color to be like a backdrop that will allow me to bring in brighter colors, like teal, turquoise, fuschia, etc.

I like a darker color like the ashwood moss. Paint all of your walls and your ceiling the same color. When you do that it is hard to tell where the walls stop and the ceiling starts and it will not make it feel as vast and canyon like in there.

I find that dark colors in a small space can be really cozy. Use lighting and pops of color in artwork and accessories to brighten it up.

Benjamin Moore raccoon fur is my powder room go to. It would look good with your vanity top too. The color of the pillows and flowers in your 3rd pic would look great against it.

Kendrah - I love your recommendation & I will try that color on in the visualizer. I’m not really concerned about it being dark - you must have a light on in there as it is. Thank you!
BeverlyFLADeziner - I love last inspo pic, maybe it’s something dark on the wall above the toilet to carry the vanity color around. And, the pink & green.
Thanks to you both!

Tiny room with a 10' ceiling? I would strongly consider dropping the ceiling. How tall are the doors?

Dropping the ceiling is not an option; thinking of painting it dark, though…