Les Schwab is not perfect, however if something is not right you can go back and they will take care of it. I had to get new tires on the rear one time and they put the wrong size on, luckily the car went in to the dealer for some work the next day and it was discovered. Correct size was put on which cost more, but they ate the extra $'s. Always shows you can never be too careful, another thing that keeps me going back is that other stores out there can be much worse. I believe the Les Schwab employees are more motivated since there are more opportunities with that firm to advance. Generally I have had good service from them for many years, and they have won the JD Power award for customer service for several years running. They will happily check tire pressures for you whether or not you bought those tires from them. They do not want to have unhappy customers, so I would write a letter to their head office.
Another thing going for them is that they are an Oregon based company, and as I live in Oregon that matters to me.