Thanks everyone. I looked at all that folks suggested and none are quite right. Definitely don't want pumps in the summer heat -- it's gotta be sandals. Love the Aerosoles, Crankin, but they're a bit dressier than I was looking for at the moment. Some of the Keens looked promising and were cute, but reading the reviews, sounds like they would likely be too wide. I found a few on Zappos I'm considering. These are probably the top contenders at the moment:

http://www.zappos.com/trotters-kat-l...fcTest=fcl%3A0

They have velcro straps so could be adjusted somewhat.