If I were in your situation I would chose a tan or brown color to paint the walls. I just finished painting my house and I went with a light brown color and it made my house look a lot nicer. I use to have white and I hated it. I highly recommend light brown.

Seeing that green is a natural color, it would look good with other natural colors. I would suggest a lighter shade of green perhaps. A light brown would look beautiful with this green. A dark brown might work even better. It would give your room a 'woodsy' feel. It would seem very comfy and inviting. If you would like your room to pop a bit, maybe even go for a reddish brown, as red is the compliment to green.