Dennys and 59 Cent Diner seem to be decent. Wireless is pretty strong and food is decent They don't bother you for being there too long Rocket River
If you have a smartphone there are many apps that show places with free wi-fi, along with user reviews and such
Schlotzsky's and Panera Bread. Panera Bread has a time limit during busy hours though. I think from 11-2 or something.
Heck, my Thursday office is McDonalds for two hours followed by Rodgers for a third hour.McD's never hassles me and the room at Krogers is quiet for concalls.