Are you wanting to participate or just watch? I know there's one in the spring sometime in Hood River... I don't remember what it was called but it was a really nice rated hunter/jumper show. I only went once but ever since then I've wanted to go again. Haha This probably doesn't help you too much though...
ETA: I looked it up and it's called the Hood River Classic.
Other than that, I've never heard of any shows around here but I'm not really in the showing loop. I wish I was though! But I've just never been able to connect with the right people it seems.
Fabio - 13 year old Arabian/Lipizzaner gelding
Hazel - 14 year old Angora goat
Atticus - 4 year old LaMancha/Alpine cross goat
Rest peacefully, Lacey.