Matt,
You have a lot of options. As you mentioned, you have the Yakima, Rocky Ford (which
is fun during the Summer), Lenice/Nunnally, Coffee Pot Lake, Amber Lake, Crab Creek,
Spokane River etc.
Living in the Spokane area, if I had to recommend an area I would say for close to
Spokane go Amber Lake (email for specifics) or the Spokane River. Along the route,
then check out Lenice or Rocky Ford. However, if I had a day to kill, I would drive
the extra 2 hours to the St. Joe River by Avery, ID. It is fishing the best by far of
anything in the region. Again, you can email me for specifics.
Have fun on your trip.
Mike