I'm not sure how intense the bluish-teal guest bedroom color is. If fairly deep, you need to go a few shades lighter in the bathroom. Bright colors will bounce back in a small room; dark ones will suck in all the light.

The bathroom mats could either be a darker version of the wall color, or match the shower curtains.

I have 500 years of house decorating experience, and a house that is perpetually half-finished [Eek!]