Here's an interesting article from "Preservation Online" about cities that have managed to force McDonalds, et al to conform to their design ordinences and be respectful of historic neighborhoods.
http://www.nationaltrust.org/magazine/story/index.htm
Here's a quote:
The key to making sure chain stores don't take over older areas is design ordinances, says Fleming, something he says many communities still don't have. "Towns are getting more sophisticated about their 40- to 50-year-old neighborhoods and are becoming concerned about the issue."