Keep an eye on the Big Thompson gauge for frequent November releases for maintenance of the plumbing parts. Big T is about an hour from Denver. Look for at least 300, though some people run it much lower. Class III-V.
Also, just upstream of Shoshone is Barrel Springs which may or may not be running, depending on how much power they're generating. I don't think there's a way to know without getting a visual on it. Class IV+ and about 2.5 hrs from Denver.
The Royal Gorge (III-IV) is often runnable this time of year, but not so much this year. A little over two hours from Denver.