Summer before last, took Neb. Hwy 2 all the way to Hwy 20. Good scenery, almost no traffic. Several towns along the way have city-operated campgrounds that are clean and inexpensive.
To cross Wyoming, it depends on which Yellowstone entrance you choose. We went through Gillette and Cody, Wyo., because we wanted to visit the Buffalo Bill Museum in Cody. I recall good roads along that route. We also visited Badlands NP and Devils Tower along the way. But if you want just to go straight to Yellowstone then the road through Casper would be faster.
