All very good information and so much to consider. I am now thinking that Venice is out of the question. Our group would rather spend more time taking in the area than spending two days of our vacation on a train to get there.
It sounds that 2-3 nights in Munich is advised. Some places the group mentioned were English Garden, Marienplatz, New Town Hall, Victuals Market, Nymphenburg Palace, Munich Residenz, Rathaus-Glockenspiel, Chinese Tower, Neuchwanstein Castle. Keep in mind we've never been to Germany so this is all based off of online research. Will that be enough time to explore the city and do some day trips?
Thinking of either heading to Salzburg and possibly Vienna for a few nights or heading the other way staying in Germany and checking out Regnsburg, Nuremberg and Bamberg as possible options. Or would it be an option to skip Vienna and do Salzburg, Regnsburg, Nuremberg and Bamberg? Curious people's thoughts on this route and potential places to stay over vs day trips.
Any information on trains, types, navigating, booking etc would be super helpful.
I appreciate everyone's input this far - it really helps put things into perspective.