while not exhaustive, the free wifi locator website may have some useful information for you.
http://www.wififreespot.com/
The list of hotels can be used to leverage the one you are staying at ... possibly
http://www.wififreespot.com/hotels.html
I've never used openwifi, but they may have something useful as well.
http://www.openwifispots.com/
found a google map app as well:
http://www.gwifi.net/