With my $600, I opted for the Trek 7.3 FX flat bar road bike ($529.) Rode it home yesterday (about 15 miles.) I felt the riding position was more comfortable than my old out-of-commission Trek 1200 road bike, but more aggressive and responsive than I would have expected from a flat bar bike. Except for catching too much air, I was very happy with the performance, considering I was carrying a load on the rack and the bike is heavier than most road bikes.

The flat bars were a compromise for value, but they were actually quite nice for my commute home. Shifts very nicely (Shimano rapid fire,) 48/38/28 triple and 11-32 cassette. Plenty of gear range, probably more than necessary except for heavy loads/extreme fatigue. Tires 700x32c. Glossy black.

This is a great utility bike for me. Thanks for everyone's input, I love reading about other's bikes and experience. (Of course, you all know there will always be more bikes! )