A new client is a national franchise chain in the service industry. They have locations I'd say in about 25% of the U.S. - so obviously a lot of opportunity for this company and website traffic. I am making the recommendation that they should build out service location pages for areas where they currently do NOT provide service because I feel they could get rankings very quickly and could put up AdSense and monetize the traffic. The industry CPC's are quite high.
It's a toss up between building pages and having "competitor" AdSense ads on your site and making potentially good money or not have pages at all and not making any money. I guess there is a branding downside to building pages in areas where you don't have service, but I don't think the industry where they are in is a National brands scenario anyway.
Would you try building out pages and seeing what extra income can be gained from AdSense? The other reason to build out these pages is because new locations do open up frequently and "building them ahead" could help with organic traffic sooner versus later.