I test road the bike two days ago, and the frame was on the upper limit of size for me (I think), but it still seemed to fit. Here's how I checked it -- please let me know if this is the right strategy -- I stood over the highest point on the top tube and had space to pull the frame upward without immediately hitting any important parts.

The guys at the LBS next door to me recommended a 19" frame originally and commented that my legs do seem longer than the average. My pants are 32" long if I do the "it should just graze the top of your shoes" fit.

I'm certainly new to all this, so please let me know if I'm thinking about the sizing the wrong way.