Yikes, the thought of biking on Westheimer scares the bejeezus out of me.
Personally, I'd load the bike up in the car and head to one of the trails. Bray's Bayou and White Oak Bayou are my favorites right now. I plan on doing some road riding too, but will probably head out on one of the organized club rides in the country rather than peddling around on the major thoroughfares in town. The fruit loop in Memorial offers some good riding too, but I tired of going around and around the same path pretty quickly.