Vienna offers the things that big cities offer. My cousins who live there have given us great guided tours but in the end was good but not great. The Romantic Road is not that scenic, visually it's just another road but with you interest in back road type things, the alte stadt in Rothenburg is a place you will never forget. The trick is to spend at least one night there. The town is usually loaded with day trippers but about 5 o'clock they all get back on their buses and the ambiance slides back a couple of centuries. Use Rick's guide book. I don't know when you are going but if you can get into the Altfraenkishe Wein Stube it is a really neat place to stay ... 600+ years old and cute raised to a power. The only problem is that it is in Rick's book so you need to reserve now. By all means take the Night Watchman's Tour, it is absolutely the best and most enjoyable history lesson you will ever have. Assuming you will have a car, it's a good idea to take the short drive north to Creglingen to see the carved alter at the Herrgotskirche, it is considered to be Tillman Remenschneider'd ultimate work (even better than St.Jacobs in Rothenburg). Dinkelsbuhl to the south of Rothenburg also has a nice old town, but there is a reason they call it Rothenburg's little sister
As for flying home, Rothenburg is only a couple hours drive to Frankfurt which is a major airport and is well served in terms of international flights.
Have a great trip and don't forget Lauterbrunnen while you are in Switzerland.