We will be traveling from Oberwesel to Stuttgart in mid-September, but in between we wanted to stop for one night. Should we stay on the straight path to Stuttgart and visit Baden-Baden or shot over to Wurzberg or Nuremburg? Is it worth it to travel sorta out of the way for one of those towns? Or are there other towns over these I should be looking into?
"Or are there other towns over these I should be looking into?"
Are you arriving in the evening and leaving in the morning for Stuttgart? Then it probably doesn't matter too much where you stay as you'll have little/no sightseeing time.
Baden-Baden is interesting to spa-goers and high-end gamblers. Wuerzburg and Nuremberg have a lot more for general-interest sightseeing types.
But even with part of one day which includes those extra driving miles, I'm not sure it's worth the remaining time you might have to visit these places. I'd look into some nice places that are roughly on the way between Oberwesel and Stuttgart. Which you pick depends on your interests.
Mainz and Speyer: http://www.en.romantic-cities.com/Cities.5616.0.html
Ludwigsburg: http://www.schloss-ludwigsburg.de/en/home/
Bad Wimpfen: https://upload.wikimedia.org/wikipedia/commons/1/16/Bad_Wimpfen_19600424_1.jpg
Ladenburg: https://upload.wikimedia.org/wikipedia/commons/9/93/Ladenburg_Marktplatz_20100704.jpg
Not far outside Stuttgart is the Black Forest town of Calw: http://www.deutschland-reise.de/imperia/md/images/deutschland-reise/baden-wuerttemberg/sehenswuerdigkeiten/calw_420x315.jpg
We actually have more time then I realized. We would arrive there (wherever that may be) on 9/13 (probably leave Oberwesel in the AM after check out) and leave AM of 9/15 for Stuttgart. So, we would have 2 nights wherever we go...
Also, thank you for those other suggestions! I will look into them!