Before you make extensive plans you will want to consult with a Canadian immigration attorney. Although, based on my understanding, the reduced charge should not be a basis for barring entry, the border guards don't know enough about their own immigration law. They only see a record that says DUI and turn you away. As an aside, I hear many stories where the individual is not the driver and the Canadian authorities do not notice their DUI record. I personally would not a whole vacation to depend on whether the authorities notice me though.
At your service,
In the past, we have called the Canadian Consulate for clients. They have been helpful. I would not just cross my fingers and hit the border.
I assume this is in Kitsap County. See if your current counsel has any room to move with the Prosecutor about alternative resolutions. The Kitsap Prosecutors are actually pretty understanding about that issue.
Best of luck.
Sign up to receive a 3-part series of useful information and legal advice about DUIs.