I am a Canadian planning a long road trip west across the northern United States across Montana and into Seattle. ...
Anyway, I need brake pads and rotors for my beloved 04 Mazda 6 wagon
If anyone had advice on what I should buy and where, I'd love to hear.
You might get more and better responses in the Brakes/Suspension subforum than here. There is a current thread going on there about Chinese-made rotors, and I posted a separate thread there recently about the four new rotors and sets of pads that we put on our '04 Sportswagon last month. In the time we have owned our wagon, this is our fourth set of front rotors (serially, the OEM that came on the car, made-in-America Raybestos PG, made-in-Italy Brembo OEM-style, and now EBC Ultimax) and our third set of rear rotors (serially, OEM, then-Italian Brembo, and now ATE PremiumOne). (We go through brakes fairly quickly, because we live atop a steep hill.)
We have changed pads when we changed rotors, and have changed rotors when we changed pads. Until this change, we used superb PBR ULT pads (sold through a different marketing channel. the identical product is known as Axxis ULT pads). This time around, we chose StopTech Street Performance pads instead, and they, too, are excellent. See my thread in the Brakes/Suspension subforum for more detail.
Coming from Saskatchewan, you of course
never see cold mornings, so I guess that you can get along with some of the so-called ceramic pads which need warm-up time to grab in cold weather. [/irony] Not a choice that I would make if I lived up there.
If you are going to Washington State, you may wish to contact ImportRP, which is situated there. It is a mail-order company, but they may allow you to pick up at the warehouse; it cannot hurt to ask. Their prices generally are better than Pep Boys, I think.