Tried this a few months ago. Bloody expensive, IIRC daily rates for a 6 year old 1100GS were about Can$150.00 per day.
Other problem was that there are plenty of rental outfits in the Pacific North West, all with flash websites etc but none responded to our e-mails.
We also considered going to Colorado but encountered similar problems, mainly cost though. If anything, we found that the US was even more expensive than Canada.
As a guide, I hired an 1150RT for a week in Germany last year. Cost was either 525 or 575 Euros per week - that was the rate for an 1150R but they had none available, so they let me have the RT for the R rate, should have been 600+. K120OLT was in excess of 800 Euros per week. Another factor to consider is daily mileage limits - the RT I hired had a limit of 200km per day / 1400km per week - pretty useless when I was going to France, Switzerland, Italy & Austria before returning the bike. Even with shortening the trip slightly, I clocked up over 1,600km but somehow, the speedo cable became disconnected at 1,320km

The reason - the excess was a staggering 40 cents (25p) per km - I saved about £70.00 due to the mysterious cable disconnection...... Some of the US & Canadian rental outfits also had mileage limits.
Other option, if going for a couple of weeks, hiring is your only real option. Any longer & you may wish to consider buying a bike there & selling before you leave. You may be able to strike a buy back deal with a bike dealer?
I recommended this to a guy from Hawaii via Horizons Unlimited. I recommended a K100, I found one in Coventry, he bought it & covered about 3,500 miles through Europe in 3 weeks. He's returned home & I'm selling it on his behalf & will forward the money to friends of his when it's sold. At the most, the use of the bike will have cost him about £250 - £300 max for the month he used it, mainly due to dropping the bike & causing a little fairing damage.
Steve