You need to compare the price of passes with that of point-to-point tickets.
Looking at individual tickets, know that there is a discount for advance purchase of non-exchangeable, non-refundable tickets (although the discounts may be gone for your dates). Furthermore, the advance tickets have additional discounts for 2 or for 4 traveling together; full price tickets are per person. For instance, when two of us went from Berlin to Dresden, the full one-way fare was €38 per person, advance purchase for one was €19, and advance purchase for two was €29. So, on this round trip, we saved €94! Of course, if the discounts aren't available or if advance tickets won't work with your plans, then passes become a better deal.
Looking at passes, since you are traveling in pairs, you can get one or two Twin passes, which will be cheaper than two or four individual passes. Since almost all of your travel is in Germany, you would want to get Germany passes, then just pay separately for the portion from the German border to Zurich. Note that while Salzburg is in Austria, it is a border station and is part of "Germany" for pass purposes.
To get P-t-P prices, use the Bahn website, following Rick's directions here.
Here is German Rail Pass information.