ive lived in the South for my whole life, and wonder if the southern tier is really a nice, refined route, especially being through the limited roads that seem to run along the coastlines. i feel like i would rather take the transam or if the weather is right, the northern tier, or just find my way through the southern and southwestern usa.
is the southern tier nice, or would you rather take another route?
I have done the ST and the TA so I can offer an opinion based on first hand experience. Bear in mind that it is just one opinion though.
I found the scenery mostly pretty dreary much of the way on the ST. I like trees and other greenery. I also like lakes, rivers, and streams. The ST had very little of any of those for more than half of the route. It was somewhat made up for by great food, nice people, and the ability to do the ride in winter. There were very few places that were pretty west of Del Rio IMO. It got better east of Del Rio for me when things greened up a bit and I liked the Gulf coast pretty well.
The bottom line for me is that I would never do the ST again unless I really wanted a winter tour. The TA on the other hand I would love to do again. I can't speak to the NT from personal experience, but suspect it is more like the TA.
Edit: I should have mentioned that I do know folks who love the parts that I consider completely bleak and actually prefer them over the places I like.
One of the big reasons I started touring was to see other places, other scenes, other terrain. If you want to tour for similar reasons and feel like you've seen what there is along the southern (southeastern) coast, then it's time to plan to go somewhere else. The TransAm has good variety (including no more than a week each of endless Ozarkian foothills and endless Kansas plains). Alternatively, you could start in central Texas and go west on the ST to see some different terrain (at least three kinds of mountains by my count, although that's multiple airplane trips in my case).
Funny thing is, after seeing a bunch of different places, my next bike trip was back near home in the southern Applachians.
In photos the Northern Tier and TransAm look so much more scenic than the ST. If you Go to Crazyguyonabike you can watch slide shows of photos of each route. This will give you a sense of the scenery... Below is a link to a post comparing the NT and TA...
I did the entire Northern Tier once, the western portion to Glacier N.P. a second time, and the portion of the Trans Am from Missoula, MT to Fairplay, CO. I also did the portion between Missoula and a little ways east of Jackson, MT last year.
Personally, if I could cross the country tomorrow, I would probably start in Seattle, follow the Pacific Coast route to the Northern Tier just east of Anacortes, take that to Glacier N.P., climb the west side of Going to the Sun, ride bak to Whitefish, take the Great Parks route to Missoula and pick up the Trans Am there. While I would be covering some familiar ground, I love the Cascades and other mountains in WA. Also, I did much of the Trans Am through OR as part of Cycle Orgeon. Other than McKenzie Pass (which I have climbed from both directions), a lot of it didn't impress me. I am not much of a high desert fan. I also want to experience Kansas.