There is a "pet store" in the mall at CdA that has a decent fish selection and some plants. There is not a LFS I'd recommend in Spokane. At one point I could have sorta recommended Ocean View Aquatics. There is a rumor that Barbie at fishaholics.org is going to be opening a store in Spokane. Barbie used to work at Ocean View and she breeds lots of pretty rare cichlids and plecos.
Another option for you might be Barnacle Bill's in Pullman. I've been told by friends keeping fish there that Bill puts his fish through a rigorous quarantine process so you never get diseased fish from him. Last time I was in the shop he was not selling plants.
If you should find yourself in Seattle check out Blue Sierra in Issaquah.
Hope this helps.