While I have many bikes, I ride a lot so they are worth it. Other members in my family ride far less, yet I've found the Jamis line of bikes very nice. My wife & daughter have a Jamis Coda, steel frame, triple crank, nice lower gearing, flat handlebars. List is $550, though I found a leftover at the local outdoor store for 30% off this spring. I just got my son a Jamis Satellite Sport, $600, steel frame, triple, not as low gearing as the Code, drop bars and brifters.

The Jamis have really held up over the past couple of years and seem to fit your criteria.