Hi Grrrlpwr,
I live in Santa Rosa and for a nice ride in the city limits, there's the Prince Memorial Greenway, which becomes the Santa Rosa Creek Trail. What section of town are you staying in?
We are striving to become a LAB certified bike friendly city, but I'll admit, we still need some work. I highly recommend the Sonoma County Bicycle Coalitions map, created by one of the most knowledgeable cyclists in the area.
http://www.bikesonoma.org/