Try them before you buy them. Put the bindings on a board with your boot and torque the board side to side. If you can't try them at a store, make sure you can return at only shipping cost.
When I tried last years Flow's vs. the Gnu binding system, I did not like the Flow's. I found that the lack of toe side strap on the Flow's reduced heal side torsional flex compared to the Gnu's. The Gnu's heal strap also automatically loosened when the high back was pulled down which made entry into the binding even faster and easier. This was me buying my first equipment and I was able to notice the difference.
For those reasons I would recommend either this years:
-Flow Minx SE (2013 model with toe strap. other models traditional Flow design)
-Roxy rear entry designs
-Gnu Women's Line
Pay attention to stiffness too. I really like my stiffer binding since all I do is cruise the mountain just like you. Stiffer gives better control for carving. We don't need flexy noodles so we can hit rails. You might be happiest with a 5-6 flex? I don't believe companies change their flex ratings for women. I ride an 8 flex.
Binding Review: 11-12 Roxy Rock-it Power