In reply to Wolfy1987 NEWMC:
September is actually a great time to be down there, probably provides some of the best stable weather of the whole year.
What you should do really depends on how much time you have at hand
since the bavarian alps from berchtesgarden in the east to the allgäu in the west offer action for a life time.
Most real mountaineers frown upon climbing the zugspitze since the summit and the surrounding area are extremely over developed and mostly overcrowded.
(Also called the highest permanent construction site in germany.)
It is still a must see if only for the freak factor of the ski resort and tourist masses on the weekend.
You can not really say the Watzmann is the wilder experience.
Just because there is no cable car, it does not mean it's less crowded.
However september should be a good time since there are no holidays and you could do it midweek.
Definetly take two days for the traverse:
Climb to Watzmannhaus one afternoon, sleep there and do the traverse the next day.
Start early and take lots of water.
Whenever staying at huts call them to make sure there's space, even if it is just before ascending.
As mentioned, Höllental and waxensteine could be a good day tour.
Höllental ascent up to the glacier is a must see as well.
An alternative to zugspitze especially for some real climbing is
the mieminger massif just south of zugspitze.
It is on the same map as well.
http://www.coburgerhuette.at/de/Home_260
The Karwendel range is the largest uninhabitated area in europe.
This is really an area for mountain adventures.
http://www.summitpost.org/karwendel/174830