More reviews? More citations? Better overall organic rankings? Better optimized local page?
Typically, proximity to city center wins many battles. All things being equal, as you noted, I would investigate the citations, work on some reviews and see where you can tidy up your local page. Just don't stuff keywords into your title ;-)
Also, your search query is different. If the keywords match better with your competitors pages than yours, of course they will win. I don't run enough zip code queries to provide more feedback. Are your analytics showing that many people are reaching your site via zip code searches? If so, maybe consider using the zip code on your site (footer) if you have not done so.
Last edited by Lb1878; Jul 5th, 2011 at 10:04 AM.
"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime." Chinese Proverb