What time of year exactly? I'll be in that part of Washington the first week of June with some friends, you're welcome to tag along.
As others have said you really don't need a guide. Book a room at the Best Western in Colfax, WA. Grab the local chamber of commerce map for photographers from the hotel front desk. Mark the hotel in your GPS, and head off into the hills until you see something neat.
Steptoe Butte is the classic place to go for a sunset, and is absolutely worth one evening. Other than that though, just drive around the back roads.