We actually have green (sage-ish), purple (plum-ish), and cream in our bathroom right now! I was originally going to do green, purple, and yellow, but then found out that yellow looked kind of weird with the green. Too much like the Green Bay Packers. So I went with cream instead. So if you went with yellow walls in the living room, definitely go for a very light color, I think. I'm not a great interior decorator, put maybe a light purple paint would look nice, then you could decorate with some purple flower pictures to tie the green couches/fireplace and purple together?

That's my meager two cents. :)