I've driven lots of I-20. Never made it all the way to the East Coast, but I catch it a lot in Texas and take it to Shreveport and points further East. It's pretty, but as Michael said, it goes through much more frequent patches of rural America than I-40. As for prettiness. It depends on what you like. As I said I-20 passes through more rural areas, but I-40 hits a lot of cities. I tend to shy away from large cities, but being from Dallas, you may have a different perspective than me.

Laura