We are planning on going from vienna,austria to gamrisch-partinkerchin, germany via train. however,we would like to stop over for a night to break up the trip. were would be a nice place to stop? we have been to salzburg already, as well as, munich, does anyone have any suggestions on places to visit that are near gamrisch?

Mittenwald is a delightful town, but it is right in Garmisch's backyard, so that's not a very logical stop.
The most logical is Innsbruck where you'd probably have to change trains anyway (or you could with the shortest route).

Typical routing would be Vienna to Garmisch via Munich, using Munich for a one-night layover. Alternately, you might go from Vienna to Salzburg for the one-night layover. Salzburg would also provide an option of perhaps a 3 hour stop in Melk for a morning visit to the Abbey on the Danube and lunch with onward travel to Salzburg for afternoon sightseeing in the old town and evening dinner

I'm not sure why the routing through Munich would be the "typical" since it takes longer and usually requires an additional change of train in Salzburg. Why not take a direct train to Innsbruck (5 hours) and another direct train to Garmisch? That's the shortest (timewise) and the easiest routing by train.

Sorry. Hit post too soon. I meant to add "especially since Munich and Salzburg are the two cities that orzo said they'd already been."