Germany 2025 Sept and October 3 week Itinerary

We spent a weekend in Hamburg. The best bit is Miniatur Wunderland - the world's largest modal railway. The rest is interesting, but not rivetting, unless you have a specific interest.

Three weeks in Germany during Oktoberfest sounds like a fun trip. I suggest you reduce the number of places you stay overnight. Each change of hotel, b&b, or apartment takes up too much time. Many places require a morning check out but then your next accommodation requires a later check in time. Plus, packing and moving luggage becomes a chore if you're doing this frequently. You have a number of stops that are close enough to become easy day trips from a central location, such as Bamberg, Nuremberg, and Regensberg.

German trains are efficient, comfortable, and relatively affordable and I don't see any destination on your list that would require a car. I don't know your city of origin so I can't look up flights, but you might consider flying into Munich. Then you might re-arrange the order of your destinations to Munich, Heidelberg, Frankfurt, Rothenberg, etc. If you've not already done so, the Deutsche Bahn website is very helpful in figuring out travel times and the most economical way to travel.

As for specific sight-seeing suggestions, tell us your interests and preferences. Museums or no? Art? History? Music and local culture? Independent sight-seeing or guided tours of sites?

Resenberg????

Stay in Mainz prior to Heidelberg; alternatively, instead of Michelstadt or BACHARACH, why not stay in a nice old-world wine town that's right on the way to Heidelberg?

There are a bunch of them on the Bergstrasse route, some right on the railway line from Frankfurt Hbf to Heidelberg. You can see the train route and learn about these towns at the link below:

https://diebergstrasse.de/storage/2025/04/Holiday-Route-2024.pdf

The 9:06 RB train from Frankfurt hits Bickenbach first and later pulls into Heppenheim at 10:00. That would be a good place to stay IMO. Catch a train to one or more of the other towns on the same route that same day if you like.

When you wake up in Heppenheim the next morning, the same RB trains will get you to Heidelberg directly in 40 minutes. It couldn't be simpler.

The Heidelberg fest is a fall festival, not an Oktoberfest. That's a Munich-specific event.

Skip the stops in Goslar or Celle--if you are doing Quedlinburg, you don't need them--and spend the nights in Hamburg with day trips to Lübeck and Schwerin. You'd be missing a lot of really cool stuff in Hamburg for more time in the lovely but much smaller Lübeck. You can still do Schwerin on the way to Berlin.

In addition to experiencing Oktoberfest in Munich you should look at the Volksfest in Stuttgart for a similiar, but somewhat lower key celebration. Regarding Bamberg, spend the night and enjoy the unique beer culture there as well.

Agree with you plan to blend D-Ticket and ICE tickets. I will be doing the same on my three week trip in September and October as well,.