This room took less work than our kitchen, but let's be honest; it makes me just as happy! Originally there was wood paneling in this room too, so after we re-drywalled, we gave it a couple coats of our favorite color: white. White is so under-rated. Even in a house with two black animals, you couldn't convince me that white isn't the best choice.
We left the white speckled tiles that were already there. Even though they're not perfect, they're serving their purpose perfectly. We did re-tile the trim. It used to be a sea-foam green, and while there are worse colors, the black and white is the timeless look we were hoping for.
We've made it modern with a trashcan from Fab, a shower curtain from Target, a light fixture from Lowes, and a mirror and shelf from IKEA. The art is a watercolor I painted to add a dose of color in a mostly white room.
If you're going to have a house with only one (basically tiny) bathroom, make sure you give it all the attention and love you can!