Discount Tire is my top choice for tires & basic tire repair. When I've had a slow leak they diagnosed the problem, patched the hole from the nail, and charged me.... guess how much? $0. Just a smile, a firm handshake, and a polite reminder that they would appreciate my business when it is time for new tires. So, it's no mystery where I go for my tire purchases.
Recently they were very helpful with acquiring a tire that was no longer produced, and went so far as to have it shipped from California. On my wife's car they gave me a great deal on a set of Michelin Pilot Sport 2's, saving me a lot of money over the dealer and some of the other competition.
Appointment is a good idea but I've had equally good luck by showing up right at the opening time. Location is on the SW corner of the 101 & 59th Ave., in the shopping area behind Del Taco that also has a Staples & Home Depot.