I actually think it's important to see Tevinter. Not only will we get to finally see what it's like more clearly but it will also, we'd get a better sense of the scale of the ongoing Qunari/Tevinter conflict. The north of Thedas in general always struck me as more interesting than the south, and the inevitable Qunari conquest of Minrathous would be more meaningful if we get to see the place firsthand and experience the place to truly appreciate it's significance.
A DAI style map that covered say Tevinter, Seheron and Rivain (maybe even the Anderfels) sounds like it would be amazing.
Given the parallels to the Eastern Roman Empire, I would expect grand architecture, a lot of history & a unique look at Andrastianism from the Black Chantry. Perhaps they'll even speak a different language and lower themselves to speaking in common. Magic and magical artificats that make what you'd find in a normal Circle's basement unenchanted vendor trash. Basically, a grand sense of empire.
But underneath that, you have slaves everywhere, citizens being forced to sell their children into slavery. Blood magic sacrifices and duels in the middle of the street which cause a large amount of collateral damage on the average man walking by which is completely looked over. Look deeper and you see the agents of the Magister always pushing and prodding at Southern Thedas and Par Vollen looking for more slaves for the Empire to run on.