NorthWesterner here. Portland or Salt Lake would be a bit of a drive if it's just two of us! I could have a bigger meet here at work, there are two other 'Treps in the parking lot.
I was planing to visit that area of Wash. I would Say that Spockan(sorry) would be a good mid point for some guys in the mid west to drive over. It only a 8 hour drive for me. But the late summer would be best. Dam hot on the flats