My wife and I are doing a month long honeymoon in August. We check out of our Munich hotel on the 19th and have 4 nights to explore Austria before taking the train along the Brenner Pass from Innsbruck to Venice on the 23rd. All we know for sure is we need to be in Innsbruck on the 23rd. We want to see Hallstatt and experience the Salzburg festival. How would you spend your time between Hallstatt, Salzburg, and Innsbruck?
We spent 2 weeks in Germany and Italy last summer taking day trips from our central apartment locations in both countries. We had one day scheduled for Hallstatt and Salzburg. You really need a full day for each. I wish we could have spent the night in Hallstatt, it is perfection and one of my most favorite days on our trip. When in Italy if you can get to Lake Garda it is also lovely, you can drive all the way around the lake or take the car ferry back across, there are 2 ferry ports on either side of the lake.
I'd go to Salzburg with the Bayern ticket (27 euro for 2 after 9 am weekdays on regional trains) and go to some festival events that strike your fancy. Go to Hallstatt, then to Innsbruck on the Austrian equivalent Einfach-Raus Ticket (35 euro for 2-5 people after 9 am on regional trains).