Ironhorse - Thankfully, I was able to round up a PDF of bicyclist-rated roads in Lexington. The ratings ranged from "Excellent" to "Acceptable" to "Marginal or Not Suitable". I combined that with Mapmyride.com to get a good idea of distance.

There are a few places where I'm pretty much stuck dealing with heavily traveled roads, but I tried to minimize my time spent on them. I'll be able to adjust for that in the morning (just leave early), and I'm going to look for an alternate afternoon/evening route that may be longer but should allow for some relaxation.