If we're just talking geography/climate and putting politics completely aside, I would say Summerset Isles..? According to the lore on UESP, it has buildings made from strangler vines and ruins made out of coral. And on the wikia, it says the capital has glass buildings which look like insect wings. I feel like all that would be cool to see, but I wouldn't expect the locals to be particularly hospitable.
I would not want to go to Black Marsh. I can't stand humidity and I would be miserable in a swamp.
Elsweyr sounds interesting, as I would love to experience khajiiti culture! Valenwood also sounds awesome with the migratory trees and such. Finally I think the Summerset coast sounds interesting , although I think I would find the Thalmor distasteful. I would most want to visit Akvair, even though it's not part of Tamriel.
Definitely Valenwood! The scenery would be stunning and the completely untamed wilderness would be fascinating. I think it would be very cool to experience the Bosmeri way of life. Also, I'm sure most people would be rather friendly- if you didn't kill the plants, that is.
Or if you looked tasty...
Same as Tae, Black Marsh. (It's an Argonian thing).
Then a trip to Skyrim to visit a certain redhead in a certain hall in a place called Whiterun. From there we'll visit the under forge. After that we'll have a trip around the plains at night to watch the stars. "(Yea right!!!).
Definitely Cyrodiil. I mean who wouldn't want to visit the Imperial City and meet the people there? Make some new friends, learn from the libraries (meeting Richard), and so on.
If there's one province I'd like to avoid, that'd be Skyrim. Well, for now. There's still the civil war going about and I'd like to stay somewhere peace and well-civilized.
I think Elsweyr is actually nice and I'd like to visit there sometimes.