Canon City to Salida goes up the Arkansas River valley. It's absolutely gorgeous, but the traffic can be heavy. I suggest you divert through Royal Gorge to get off the main road for a while, although it will cost you a Royal Gorge entry fee. On the other hand, you get to ride your bike right across the Royal Gorge bridge.
From Salida, you can shoot up to Buena Vista and Leadville. I think the road has a shoulder most of the way (at least as far as Buena Vista), but again, the traffic can be heavy. You'll be riding right up alongside the collegiate peaks so you have constant spectacular scenery to your left. You might encounter headwinds.
From Leadville, you go over Fremont Pass and drop into Copper Mountain and Frisco and reconnect with the TransAm. (Or, if you want a bit longer route, you can go over Tennessee Pass into Vail and then over Vail Pass to Copper Mountain. The entire route from Vail to Frisco is traffic-free.)
The main TransAm route is pretty lonely from Canon City to Fairplay, over Current Creek Pass. Then you go over spectacular Hoosier Pass into Breckenridge and into Frisco.
Either way is great. The route through Salida adds about 40 miles.