This is our first time to Germany. We are a family of 5, 20yrs thru 50. The only thing we know is that we would like to spend 1 day at octoberfest. We have 6 nights in late September for our trip. I have no idea where to begin. RS says you only need 2 or 3 in Munich. My question is where do I go from there? Do I use Munich as my base, or rent a car and drive around to different towns, spending the night in different locations? Please help!
Six nights would not be too long to use Munich as a home base for it's regular sightseeing, Oktoberfest, and nearby side trips. But hotels are more expensive and harder to find in Munich at this time, so you'll probably book fewer nights there and then a couple in Salzburg or any German town that also interests you. Searching for hotels now may answer the question, if you haven't already found one.
Perhaps Salzburg or Vienna?
Venice is one hr flight from Munich. Three nights there would be easy to tolerate
Have you looked at the RS tours that include Munich and see where else they go to give you ideas? With just 6 nights you will not be able to do an entire tour, but in can give you inspiration for another destination.
"The only thing we know is that we would like to spend 1 day at octoberfest."
Right. Well, that's one day. So you have some more studying to do on how to spend your time. In the Alps, look into Berchtesgaden for a few days (which would allow for a day trip to Salzburg.) Garmisch-Partenkirchen and Mittenwald are also good alpine destinations - for more than just a day trip IMO.
Keep in mind that at O'fest it's not only your lodging that's pricey but onsite beer and food too. Minimum per-person purchase amounts in the tents starts at around $40, I believe - which gets you 2 liters of beer and half a chicken, or some similar arrangement.
If you make it to Garmisch (about 1.5 hours by direct train from Munich) the Fraundorfer Inn puts on a Bavarian Evening with music and traditional dancing: http://gasthof-fraundorfer.de/english/restaurant.php
There are many other destinations you might consider as well, Bamberg, Nuremberg, Regensburg among them. Herrenchiemsee in Prien (about 1 hour from Munich by direct train) might be a good day trip if you prefer to stay in Munich; the palace is on an island, so you'll have a walk to the lakeside harbor through Prien and a boat ride as well:
http://www.herrenchiemsee.de/englisch/tourist/index.htm
https://www.nuernbergluftbild.de/images/luftbild/K07090700.JPG
There are hidden gems in Regensburg. Really old, old, and not so old churches. Museum. Short river cruises that do not cost an arm and a leg. Is that a Roman bridge? Can not remember. Take a look online. Who knew, when busing to Regensburg, there is a theme park stay out in the middle of those corn fields and two young ladies were going there for several days! This was a big bubble with a hotel inside!
We also took a day trip south of Munich to a lake town. Community gardens along the train ride. If it had been clear we would have be able to see the Alps that we have been to before. If it was a bit warmer and less windy we could have taken a boat cruise to see the ALPS in the distance. We went for a walk near/far city and lake! Local market. Checked out (visual and smell) where the locals were eating and had a wonderful lunch. Each pensioners could eat a strudel with cream all by themselves! We shared one.
Munich is a great city to visit with exceptional nice helpful locals. Use local transportation!
Why did we end up in Regensberg? It is a short bus ride to Prague and it breaks up a long trip to Prague from Munich.