We will be arriving to Munich via plane on 4/18, staying in the main part of the city and then taking a train to Salzburg on Sunday 4/21. Would it be cost effective to buy the D ticket or should we pay as we go? Thank you.
2 D-tickets = €98. OR...
1 Bayern Ticket for Munich > Salzburg for two: €39
1 airport > city day ticket for 2 for entry into and travel around Munich on Day 1: €29.
Not sure what your transport needs will be in between. But if you have none, you will have saved €30 using individual tickets.
Not mentioned was the effort to buy it, then the effort to cancel the D ticket. All said and done, just pay as you go.
Of course, you are telling us when and where you are departing from, anywhere else in Germany you will be going, whether or not you will be using Munich public transportation while you are in Munich. All that needs to be accounted for to make an informed decision.