I'd go to the PNW either Hood River area, or the Skykomish drainage. The North Fork, and Main will be running. The Foss river if you portage Ken and Barbie is class IV. Take your play boat down the Green River near Auburn, WA, Paradise Ledge is like Canyon Doors in Browns Canyon. Go over Stevens Pass to the Wenatchee drainage. Buy "A Guide to the Whitewater Rivers of Washington.". Hit up BC for Skoomchuck, if the moon cycle jives, and the Thompson. The Olympic peninsula has good surfing at Barbwire. It's really a no brainer.