I just sent my passport off to be renewed.
I don't believe in not having a valid passport, because I believe you have to be ready to jump on a plane whenever an opportunity shows up. Over the years I have known many people who have missed a work trip to Paris, a shoot in the Maldives, a chance to go to the Greek Islands, all because they didn't have a passport.
If you have 6 months left on your current passport you need to renew it now. If you have less then 6 months you needed to renew it yesterday. If you don't have a passport, go get one now.
You never know when you will need it.
Here is an article I found on Smarter Travel.com, written by Shannon McMahon