You, me and 1998 others too! I am in Oregon and this is my very first RTR too. I am a bit concerned about adjusting to the high altitude. Most of my riding here in the valley is at 200-2,000 ft elevations. I plan to get to Colorado a week or so ahead to try to get acclimated.
If you haven't done so already, you can sign up at the RTR website for the 'My Ride' section where riders can interact, exchange info, post photos, maintain a blog etc. There seem to be quite a few riders from Denver and the surrounding areas.
Cheers.