Earl the Pearl, in bringing up a new site and comparing to an older one, has done a great summary and analysis at SeoREfugee of where local traffic is coming from:
Over the past 10 months, the largest single traffic generator search phrase has been the industry generic term. In google it has generated about 2100 visits and Yahoo about 2600 visits. About 90% of the traffic from google is ppc oriented whereas in Yahoo its all organic search.
Of visits to the site that have the same or virtually analogous business terms with a geo modifier, the clear traffic visit leader with the most traffic has been the business term with the city name, versus the business term with state names. Traffic for the most popular business term with the city (washington dc) has generated over 300 visits in this time period. Meanwhile the next most popular phrases with geo modifiers have been for the 2 states.
Of significance, prior to the insertion of google maps into organic searches, their was no noticable difference between industry terms for the generic business terms and any of 3 different most prevalent geo modifiers (2 states, Maryland, and Virginia, and one city- DC.).
It appears that the insertion of a map which has always featured this business at the top of the search page, has increased visits to the site by about 30-50% over searches without a map.
In other words, there is a significant increase in traffic to the site wherein there is a #1 organic ranking, and a map, and a ppc ad over sites with a #1 organic ranking, a ppc ad and no map.(my bold)
To date it appears that high generic rankings or high ranked ppc with geo terms in the title for generic industry terms are critical; high ranked terms for geo-modified business terms are critical, and the appearance of a business in maps within a 3 pack/10pack/authoritative map are of big help…but don’t have the impact of either high organic rankings or highly ranked ppc.
His assessment of coupons? No customer responses as they are buried too deeply within Maps to be found.