You have a nice, neutral blank slate to work with. No one can suggest colors in a vacuum - not knowing what you prefer or what is being used in the rest of your home. Maybe look through pics of similar bathrooms and find some inspiration there?

If it were my room, I'd find a colorful runner for in front of the vanity, some art for the walls and hang some towels and bars (if you don't already have towel bars installed somewhere). The logical place would be on the wall to the left of the sink so you could have art on the wall to the right?

Maybe an orchid in a pot on the counter, or another kind of plant if you have enough light - a soap dispenser or soap dish. Have fun!