Chris,
I spent 2-1/2 years in Yakima going to school in the early 90's. You have three choices over there none of which are nere by. Plan on spending that extra 1/2 year youll need it to make up for all the days you'll miss when the road trip is more important than the geology class.
Choice (1)drive to the Walla Walla about 2-1/2 hours away not the most fun river but well worth the trip. (2) Next is the cowlitz really not that far away over white pass. Usually went there once a week. (3) Try to not schedule classes on Mondays or Fridays. If you get that third day off it will make it worth your wild to drive home for the weekend and get your steely fix.

Just some words of wisdom from someone thats been there before.