Our small bathroom has white fixtures. The floor and inside the tub
enclosure are white tile with Hunter Green accents. The wood trim
around the window and door are light color natural wood.

What color(s) should I paint the walls?

Hi dunndeals,

I would go for a pale yellow.

Best regards,
Rainbow

Good suggestion, and flattering to the bathers.  You (or "she") might
watch out about doing make-up there, however, if it is going to be
seen in daylight.

There's lots of inspiration at this site: 
http://www.behr.com/behrx/inspiration/emotional_2.jsp

In one of the pictures you'll see a bathroom with white fittings and a
timber floor with a lovely pale green on the walls. That would be very
soothing, but alternatively, white fittings and a timber floor can
support a very dramatic colour too (terracotta!) This site also has an
interactive feature that is meant to allow you to 'see' your bathroom
in different colours. I registered for it (free) but couldn't get it
to load. Looks like fun, though, and I'll certainly try it again soon
and see if it's working. (Maybe their IT person is still on hols.)