My wife and I are starting to plan our return trip to Europe for the fall of 2016. So far, all we know is that it will be a 2 week trip and we want to spend a couple of nights in London and Paris but the rest of the trip is up in the air. We'd like to add 2-3 more major destinations to the itinerary with the possibility of some small stops or day trips to smaller destinations along the way. We're considering stops in Germany, Austria, and/or Switzerland. I'm just getting started here so I really have no idea what these countries are like in the fall or anything like that. So, I'm hoping that all of you experienced travelers out there can give me some guidance.
Disclaimers: My wife says London/Paris is non-negotiable. I say that we have to at least see a German castle. I've always wanted to go to Austria.