When you get to Colorado, check out Rocky Mountain National Park in Estes Park, CO (not far from Fort Collins). The ride through the park is great and you hit altitudes of over 14,000 feet. Really great winding roads and scenery. Estes Park is a nice little town too and I recommend visiting the Stanley Hotel (It's the hotel that inspired Stephen King to write The Shining and was used in the filming of the TV mini-series).
I did a cross country ride two years ago with a friend of mine and it was amazing. We were on Harleys (I rode a Sportster Iron 883 and my buddy had a Crossbones) but wish I had my '75 CB550 at the time because I would have much rather taken it. We went all the way down the East Coast, down along the Southern Border and then up through Arizona, Nevada, Utah, Colorado to South Dakota and Wyoming. Then I rode back to CT on the Historic Lincoln Highway which is a small two lane road that spans coast to coast. We covered over 6,000 miles and traveled through some great parts of the country and visited many of the National Parks. I recommend staying off highways as much as you can and instead using state roads and back roads which have better scenery and take you through small towns. Also, bring earplugs for the ride because the wind noise will wear you out after awhile when covering hundreds of miles each day. Enjoy the trip!