Austria - Germany Itinerary

Your itinerary is certainly do-able, but you're going to be moving from place to place a lot.
Have you considered renting a car at the end of your stay in Munich and driving south into the Bavarian countryside and staying one night? You might want to go around Garmish or even just over the Austria border for sheer mountain scenery. Then return the rental car in Munich and leave on the train north.

I can't think of anyplace I've been (that I've liked) where I wouldn't want more time to visit. Two days in Salzburg is good because it's small, virtually every site is walking distance from the center - I've never tried to fit in SOM though. My biggest criticism is your time in Munich. Three days is a nice amount of time, but your day trips don't leave much time for Munich itself. When you think of time, think nights. Two nights gives you one full day, three nights = two days. Generally on either end are travel days. A travel day includes some combination of packing, checking out of your hotel, getting some breakfast, getting to transportation, waiting for connection(s), arriving at your next stop, getting to your lodging, checking in, unpacking/getting settled, finding something to eat, etc. Even a relatively short four hour trip will become a full day of travel. So don't plan those as times you can see sites - at best you will be settled by early afternoon. I find myself driving more and planning a mid-day stop for several hours between nights. It sacrifices what's left of the day but breaks up the trip and adds a stop for something you may have wanted to see, but weren't willing to commit a full day (and nights) to. For a six hour trip to Liepzig, I'd add at least two hours on either end to estimate your total travel time that day and plan to arrive in time for dinner. If you're efficient, you can squeeze some off of that - but you run the risk of alienating everyone you're traveling with. You can get between Salzburg and Munich and probably be up and running by noon if you start early.

Thanks for your replies. @David, I did consider the rental car, in that Rick says it is the most efficient way of getting around Bavaria. But, as I am traveling alone, and have never rented a car or driven in a foreign country, I think I'd prefer to stick to trains and buses on this trip. It looks like (per Rick) I can get a train to Fussen and a bus from there to the castles. I'd love to hear from people who visited the Tegelberg Gondola in the same day as Neuschwanstein Castle. I've heard of people hiking from the castle to Tegelberg, and Rick says the buses continue there as well. @Brad, I hear you about the travel day thing. I'm actually a very experienced traveler, and have definitely considered what you're talking about. But, you see the length of my trip (2 weeks), the basically direct route I'm taking, and most of the trips here are quite short. I'm alone and will take leave around 9AM (no fellow travelers to alienate). So, I think you've zeroed in on the exact problem I foresaw too little time in the Munich area. To further complicate matters, the day I travel from Salzburg to Munich is a Monday, when most museums, and Dachau, are closed this is a problem! It looks like I may have to choose between Dachau and the castles. And yet, I feel strongly about preserving the 4 nights in Berlin, at the end of my trip. I'm a city mouse and wanted that quality time to experience Berlin. Is that foolish, i.e., am I going to be bored in Berlin and wish I had that extra day in Munich? Thanks again for your responses.

I think your plan is good, and no, you won't be bored in Berlin. In fact, you may wish you had more than 4 days there. I think if I dropped anything, it might be one of the days in Leipzig or Salzburg, and add it on to Munich or even Berlin. If it is a Monday, go on a walking tour or bike tour in any of these destinations. You don't need a car for any of these destinations. Enjoy the train rides and the scenery.

The day you travel from Salzburg to Munich you may consider an Original Munich Walks Tour for your afternoon.
In Berlin it is called the Original Berlin Walks. They have several walking tour themes. You meet at a certain place & pay the guide then. They can last 2- 3 hours depending on which one you choose. Berlin is sprawled out unlike Paris & London so you'll have lots of time to get around & see the city. The city & people are very welcoming and open. Hard to explain until you've experienced it.