Frank's Diner in downtown Spokane is a great place to mix with hungry locals and enjoy the amazing hashbrowns! All their breakfast food is delicious and come in quite hefty portions. They serve lunch and dinner as well and while I've only strayed once from my breakfast fair, I can recommend the patty melt to be sure.
Frank's is set in a classic train car so seating is limited and slightly cramped. But you can watch the hashbrown jockeys do their thing while sitting at the counter.