If you've got the time don't skip any of it. All sections have something to offer in terms or scenery. I didn't mind OK, wide open long runs, some sand and gravel to look out for. If you're short on time then just start in NM, that's where it gets fun and challenging. Well NV is where it get challenging, and parts of Utah.
Have to agree the last 50 on TN is nice, up until then it pretty easy, but still nice to see.