Drive further north on I-5 from Eugene and stop in at Cueballs in Salem, Oregon. The place is full of 9' anniversary and centennial tables. It's like a pool table history lesson in there.
Look in the back of both regional papers for the appropriate state and you may find something. Also, check out the list of advertisers in front. On the Break's website is an online version of their paper and they also have some OR spots.
The only poolroom in Missoula is Palace Billiards...in the basement of a building, downtown, on Main St., right across from the Courthouse. It's not much of a poolroom...kinda dingy...but they do have 9' tables. There's also
9' tables at the University, in the Student Union.