Rothenburg side trip

I would ask... why do you really, really want to visit Rothenburg? Despite all the attention it gets from the tourist industry, it really, really isn't nearly as unique as advertised... except for all the tour buses that visit and the trinket shops that service them. Although Rothenburg is a little bigger than most, Germany is filled with towns that preserve a large portion of their historic architecture, a handful or more of which also maintain their old defensive walls. Rothenburg is a reasonable stop when traveling between the Rhine and southern Bavaria, or a daytrip from one of the nearby cities, like Nürnberg, Würzburg, Augsburg or Bamberg. But if you're traveling more than two hours out of your way to visit, you've probably bypassing any number of worthy alternatives.

My knowledge of France isn't as extensive as some on this website, but I'm betting you could very easily find something worthwhile much closer to Paris. Although Alsace isn't all that close to Paris either, many of the towns there have a similar atmosphere.

There are several things we want to see there, in particular.

If you like quaint towns, Germany is full of them and they are everywhere. Take a look at the Half-Timbered route to see if any of them on your way so you aren't going so far out of your way.

http://www.deutsche-fachwerkstrasse.de/uk/cont.php3?c=portrait

You don't say what it is you really want to see in Rothenburg, so we can't tell you if the same things exist in other towns.

Strasbourg is a nice place to visit and has a convenient train to Paris. It is a long train trip from Rothenburg ( which I really like - don't be discouraged from visiting ). If you like car museums, then Stuttgart is a possibility.

You've received good advice above.

It sounds like you were thinking 1 night in r'burg and 1 night elsewhere before Paris - 2 nights - right?

Nuremberg Airport - Rothenburg - Paris (without an additional overnight stop in Germany) takes 9-10 hours by train.

Frankfurt Airport - Strasbourg (FR) - Paris takes 4 hours.

Of course, Strasbourg isn't Germany. But it's a fine place and 4 hours of ground travel is vastly better than 10 for your brief time in Germany... and this train route puts you very near some very nice historic German towns as well...

Gengenbach is a lovely Germany Black Forest town and 7-minute detour from Offenburg (very close to Strasbourg on the above route.)

Gutach is a popular destination (or overnight stop) with a terrific open-air museum - just 30 train minutes from Gengenbach.
Haslach is in between Gengenbach and Gutach.

Gengenbach and Gutach share the scenic Black Forest Railway, one of Germany's top scenic train routes. (Gutach is near Hausach on the map above.)

So you could spend 2 nights in one town (like Gengenbach) and visit another nearby German town or two (like Gutach or Haslach) and also make a stop in Strasbourg if you like on your way to Paris.

There are other old-world places (like Bad Wimpfen, near Heidelberg) which are near the FRA - Strasbourg - Paris route too and good alternatives to the Black Forest suggestions I named.

My knowledge of France isn't as extensive as some on this website, but
I'm betting you could very easily find something worthwhile much
closer to Paris.

Provins or Laon for example. Both with a town wall, and Laon has a beautiful cathedral. And Provins is a World Heritage Site.