Heber Ut to Vernal Ut includes a couple good pulls. Majority is 65mph. As you approach Vernal it gets busy (actually Myton through Roosevelt to Vernal seems like a busy road because of all the work traffic to the well fields).
Vernal Ut to Craig Co is boring. Long rolling hills, I don't remember there being any long and steep. Not much traffic.
Hayden to Steamboat is beautiful. The first few miles South out of Steamboat are also very nice but you are now getting in to the mountain driving (slower speeds, faster elevation change).
40 is a good hwy for sight seeing. I took this route from SLC to Hayden bi-weekly (I was doing contract work in Leadville and this was the quickest route on my motorcycle).