For scenery, your second route cannot be beat. So if scenery is your top priority, the Pacific Coast and the southwest US are good choices. The Pacific Coast has plentiful and cheap hiker/biker campsites. All of the national parks you mention also have camping, although not usually as inexpensive.
People are a very important part of bicycle touring enjoyment for me. In my opinion, the middle of the US is best for this. Small-town America has a charm that's hard to beat, and the people are amazing friendly and generous. I wouldn't want to miss this. Also, the TransAm is a very popular bicycle route, so you'll meet many other touring cyclists on that route, which is fun for me.
Every tour has its own charm, and it's a very personal decision.