If you're primarily targeting local business, a directory listing by location will help as the link will provide a valuable reference. As you suggest, find the best geographic entry in ODP. Also, there are often true local directories created for the benefit of local residents. Although their traffic is relatively low, sometimes they provide highly qualified traffic.
The best marketing tactic for locally-targeted sites is to do non-web marketing in the target area - leaflets, business cards, adverts in the local paper, mailshots, etc. For a business, having a web site should not be considered separately to the rest of any offline marketing campaign. Apart from local directories, there are few effective online search tools which help with marketing at this level.