DLab - I think you're on top... for now. To me, the one I have top-ranked (
#61) exudes action to green, Otherwise American colors and symbols, transportation and transportation energy. Again, I'm but one voice that will make the final decision, out of a group of 8, and I'm encouraging the others to continue developing.
If you are interested in working up a different line of thinking, would you take a look at the Clean Cities logos that are here:
http://www1.eere.energy.gov/cleancities/toolbox/logos.html It's the sun over city logo. This is the logo that many of the coalitions develop deviations from. We don't want to copy this at all, but are also considering having a logo that... perhaps gives a simple nod to that one. A logo that incorporates much of what you have included in the editions you've provided, but has some setting sun, or some derivation of a skyline it, to give that nod.
Thanks for your efforts!!