Zugspitze from Munich

All the tours that I looked up on the net have the option of only
Sunday bookings.

So if you want to take a "tour" it will have to be on a Sunday, but you can do it anytime on your own. Just purchase a ticket from wherever you are in Munich to Garmisch-Partenkirchen. The Zugspitzebahn Bahnhof, from which the trains to the mountain depart is adjacent to the Garmisch-Partenkirchen Bahnhof. You can either take the cog train or get off at Eibsee and take the cable car to the top. Go as early as you can because the mountain often is "socked in" later in the day.

Thanks for the quick revert.
I assume taking the cable car will save time?

Just a bit. From Eibsee, it is about 45 minutes to the top staying on the train. The cable car runs every half hour and takes 10 minutes, but it all depends on the timing. Since much of the train is inside the mountain, the cable car will certainly offer better views. The cost is 53 EUR per person. http://zugspitze.de/en/summer/preise/zugspitze

To get to Garmisch, you want to buy a Werdenfels ticket that costs 20 EUR for the first person and 6 EUR for each additional person up to 5 traveling together. Direct rains to Garmisch leave the Hauptbahnhof every hour at 32 past the hour beginning at 6:32 and take 1 hour and 22 minutes. The Werdendels ticket covers you both ways, and even the Munich S-bahn if your lodging is not by the Hauptbahnhof.

I assume taking the cable car will save time?

From 3th of April the cable car is out of order due to reconstruction work.

http://zugspitze.de/en/winter/news/news/cable+car+operations+end+on+2nd+april+2017_n17870

And that answers that question.

sla019: Thanks, this is the reason I monitor the Forum! We'll now be better prepared for Zugspitz in September.

Note that, unlike the Bayern-Ticket, the Regio-Ticket Werdenfels does not have a 9 AM weekday restriction, so you can get an early start.

This page shows all of the rail and bus lines that are included with the Werdenfels-Ticket. It includes the buses between Garmisch-Partenkirchen and Oberammergau and between Oberammergau and Linderhof. It also includes the very scenic bus ride from Garmisch-Partenkirchen to Kochel along the edge of the Walchensee (part of the Alpenstrasse).

The Werdenfels-Ticket also includes the Ausserfernbahn train from Garmisch-Partenkirchen to Pfronten via Reutte. This route stops in the town of Erwald, from which you could take the Austrian Tiroler Zugspitzbahn (another cable car) up the Zugspitze.