Hey, welcome to the Rockies. I'm a geographical mutt, but I certainly learned to boat in the midwest and SE (and used to work for NOC). Gary is right about the guidebook (CRC2 aka "The Bible"). When you open it, you'll see that the kind of water you're looking for is scarce out here, but there is good stuff to be had nonetheless.
*Westwater is big water class III, with one IV. It gets up to a solid IV at higher levels. Make sure you read the permit regulations carefully, as the BLM is strict about them. Kinda of a pain in the rear, but they keep the canyon pretty darn pristine. That S8 will be nicer on the paddle out than most playboats.
*The Crystal has some nice runs that are class III-IVish - Bogan Canyon, Crystal Mill Falls Run, Avalanche, and a few easy creeks, I think. (Although you'll discover that out here, people don't usually call something a creek unless it's a solid class V, as opposed to the SE, where you have class III creeks like the Tellico or Little.)
*Durango doesn't have much III-IV, but there is a little bit of that on the San Juan and Piedra over towards Pagosa Springs.
*Vail has Dowd Chute, but that is only about 2 miles long. At higher levels it becomes a nice read-n-run IV+.
*Sweetwater Creek is a mellow IV- according to CRC2.
That's about it for stuff that is within 3 hours, as far as I can recall. I haven't run all of these, but it should give you a start as far as places to look. The Gunny watershed has some stuff, but most folks go there for the creeks in CB. If you're willing to travel further, the Ark has Brown's Canyon and the Numbers, CO's best known class III and IV runs.
You can find a TON of beta on the Buzz by running a search on the river you're interested in, too.
Join up, suckas.
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