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Hi There! Not quite sure I'm following your thought here. What would you be keeping the NAP off of? I understood that your original idea was to build out separate landing pages for zip codes or build a separate website. I'm recommending against either approach. Having 2 authoritative websites (with the same business name) would potentially be confusing to both humans and bots, and building out landing pages on your original site just for zip codes sounds like it might lead to thin or duplicate content, and could even fall under Google's new doorway pages update. If you want to optimize for zip codes, my best recommendation is to find an way to work this into your existing site and existing city landing pages (as in my Monterey example). I can't think of any other approach I'd be comfortable recommending. Hope this helps!

Make big improvements to a few unimportant pages.  See what happens.   I think that this is relatively safe.

I appreciate the help. I do build quality pages. for the most part. I would not include a wall of zip codes or other spam text. I would write a 2-300 page paragraph outing the services a little more and just using 1-3% keyword density and maybe throw in some h3 tags with it.