I've ridden the NT (by sections completed 2007) and the TA (with AC, this year). I'll respond to Buddy's points.
1. Absolutely agree, TA is a lot harder than the NT. I hated Virginia and Kentucky, and was miserable until I reached Kansas.
2. There are more hostels on the TA, but there are also more long gaps with no support on the TA, such as eastern Oregon, parts of Idaho and Montana. This forced long riding days.
3. I saw a number of other tourists on the TA, but had few conversations. That's probably because I was with a group having high daily mileages (which sucked) and I didn't stop to chat.
4. I did see more foreign tourists on the TA, largely because a lot of Dutch seem drawn to it.
5. Yes, I'm part of an exclusive fraternity having ridden the TA. But I'm sour on the route for other reasons, so big deal, I rode the TA.
6. You see small town USA from any of these routes. The only cities on the NT are Cleveland, and it skirts Buffalo.
7. I agree that the TA is very different in different regions, and I appreciated this.
My big complaints on the TA are the extra 800 miles because it wanders all over the northwest, and the previous remark on Virginia. Why do we have to go to Missoula, it's not bloody Mecca. Why do we have to zigzag south then north then south to traverse Hell's Canyon? Then there's the three added days because groups are prohibited from entering Yellowstone south entrance.
As for VA and KY (and somewhat the Ozarks), I am not a super strong rider, though I have good endurance. I don't mind being last to camp, but I didn't like being late, especially when I was on cooking that night, and others had to cover for me. I had to walk a lot of the hills. I had no discretionary time in the evenings until we hit Kansas, so I had trouble journaling (to keep contact with family) and sometimes didn't have time to fix my bike. There were half a dozen times that I was actually dozing off riding and had to stop for a power nap - despite getting 8 hours of sleep most nights. Bottom line: if you're not a very strong rider, take a different route or don't go with a group that has a fixed agenda.