Train transport in Germany

To Bacharach: €12.20 each for local RMV ticket on regional trains

To Rothenburg: Day pass for Germany (Quer durchs Land Ticket) or Happy Weekend ticket (on Sat or Sun, also a day pass) = €52 or €50 respectively for two adults

To Füssen: Bavaria Ticket (day pass €31/2)

To Munich: Bavaria Ticket (same)

To Munich airport: MVV Airport-city day ticket (€24.30/2, day pass)

So the two of you could do all this for around €160 total.

The Bavaria Ticket and MVV ticket day passes allow you to use not just trains but also public transport (subway, bus, tram) within Munich and around Füssen as well

Buy all these tickets and day passes at the station on the day of travel and ride the regional trains (no high-speed equipment.)

There's no need for a car for any of these places as long as you book somewhat near a train station (or a local bus stop which serves the station.)

Wow, thank you! I thought we would have to spend a lot more. Your tips are all very helpful!

Using day passes on weekdays: Except for the Airport-City Day Ticket (which is valid at any hour) the day passes may not be used prior to 9 am.

Train schedules that can be used with the tickets and day passes mentioned above can be found at the DB itinerary search page - but you need to click on the "only local transport" box to find them:

https://reiseauskunft.bahn.de//bin/query.exe/en

Yes, be warned that the Quer-Durchs-Land ticket cannot be used on the fastest ICE or IC trains.

be warned that the Quer-Durchs-Land ticket cannot be used on the fastest ICE or IC trains.

That is not a warning not to purchase one of those regional passes (Quer-durchs-Land-Ticket or Schönes-Wochenende-Ticket), only not to try to board an ICE with one of those tickets. The QdLT and SWT are not usable on long distance trains (ICE/IC/EC).

But I think here it is a toss-up as to whether to use one of the regional passes vs. an advance purchase Savings Fare ticket. If you can score a Savings Fare ticket at the lowest price (59,80€ for two), and tickets at that price are still available for most days and times in June, it's less than 10€ more than for a regional pass, and it will save you an hour from Bacharach to Rothenburg.

On the other hand the Savings Fare ticket is limited to a specific long distance train, an ICE from either Mainz or Frankfurt, so you have to make the connecting train from Bacharach or lose the ticket.

And booking an ICE allows you to make seat reservations for 9.-€ for two seats, so you can be assured of not having to stand for two hours. But 1) the RE from Frankfurt Hbf to Würzburg is a big, double-deck train so it is unlikely to be SOL, and 2) it originates in Frankfurt, and you have 40 minutes to catch it, so you should have time to board early and get a seat.

If you're going to have data on your phone(s), I suggest getting the DB Navigator app. You can look up schedules and routes easily, and you can also purchase tickets within the app. I am not sure how it works if you purchase for multiple people on the same phone, since I traveled solo, but I would guess it's pretty straightforward. It was nice not to have to mess around with ticket machines--I could just walk to the platform while buying a ticket on my phone and the conductor scanned the QR code from my when she came past. Easy!

Of course, I have T-Mobile, so I wasn't worried about data costs for my phone. If you have another carrier with expensive data or low data caps, this is probably not the best option for you.