We have some 4 season rivers, but the real fun in Oregon is when there is some spring runoff or decent rain. Portland has a lot to offer, but there is always a little drive to get to the whitewater. The Clackamas and Santiam always have enough water for some fun, The Sandy more or less dries up in the summer. The White Salmon is always runnable, and is a step up from most of our Class II-III stuff. ( No play boating there )
There are a lot of coastal rivers that require rain to, but they can be real adventures only an hour away from home. We have an ocean that you can surf in any craft you want. Washington State has plenty to offer like the Lewis, Washougal, Cispus, Sky, Wind, White Salmon, and Klickitat. Skiing isn't much farther than Bob's hole on the Clackamas.
I've never been to Colorado, so I am biased. I'm sure I'd love it there. Here in Portland, I enjoy driving just a little bit out of town, the feeling I get when I leave town. There are so many people in Portland that don't even know that the upper Clackamas exists. There is such a difference in what the Clackamas looks and feels like above the Dams and below them, yet we are talking about ten miles that separate the 2.
Spencer's hole on the Santiam is a funnel, the river is about 15 feet wide where the wave is, great place to play. I've seen people so focused on surfing that they forget to look up and avoid the rafters and kayakers coming downstream. I spend a lot of time on the Santiam with my family in summer. Then we have some pretty good camping rivers too, like the John Day, Owyhee, and of course the Rogue. There are more, but those are a few.