A saw shop that carries a wide array of products related to trees and saws would (and does) keep me coming back. This, of course, presumes that the related products are of good quality and reasonably priced. And they must be in stock! Selling a full range of arborist supplies and tree-related pesticides, wood splitting equipment, wood chippers, and work clothing are good ways to make the shop a go-to establishment.
A saw shop that also sells wood heating stuff - stoves, fireplaces, boilers, accessories - would be a good combination and increase the value of the store to many saw consumers. They should also either handle the installation and maintenace of the woodheat stuff they sell or have a fast, reliable business that they have handle their work.
Being a full-line dealer for your saw manufacturer's product line is also valuable, so long as the shop actually knows about the products and stock parts for 'em. And if the shop also sells lightly-used products, that could keep my business in the store instead of on eBay for equipment I won't use that often and therefore can't justify buying new.
At the end of the day, I want to have to go to as few stores as possible to get the stuff I need AND I want it to be in stock when I get there. I can order stuff online at home and can often get it faster than the dealer can/will, so the ability or willingness of the shop to special order the same stuff I can get online is not of very much value to me.