I'm in Nebraska, which is admittedly a bit less hilly than CO, but we have our share of nice gravel rollers. I rode my first ever century on my single speed KM a couple of summers ago and rode it for a total of 1500+ miles that year. It is a great all around 29" platform for everyday use. It hasn't seen much use this year due to me getting some other bikes, but I just made it a fixed gear and put Exiwolfs on it and am going to use it as one of my snow commuter bikes.
I'm running 34x16 which works great on the gravel rollers and really gets your legs spinning on the flat terrain.
Cheers,