Itinerary help, Rhine Gorge, possibly Moselle?

Do you like like larger cities? We were in Germany 2 years ago and prefer villages. You mentioned the Mosel. We stayed 3 night in Belstien, it was small, but delightful. Trier and Koblenz are much larger, I believe we did laundry in Trier. They both seemed nice, but we just drove through. Cologne is a large city, the Cathedral is the main draw. Do you have Rick Steve's Germany book? He gives great advice about finding a good base.

We prefer smaller towns and villages to bigger cities but I would not be opposed to a mix. I need to order the most recent version of Rick Steve's Germany, I only have the pocket Munich one.

so it looks like driving is the fastest way to Frankfurt?

Probably. But you're using the most scenic train routes in Germany. Will you be in a rush to get to Frankfurt?

I suggest basing for 3 nights in Boppard am Rhein (which provides a free VRM guest ticket for free local train trips.) Do a day trip to Cologne from there if you wish. And I'd assign the other 3 nights to Cochem, an ideal Mosel river base for day trips to Beilstein, Burg Eltz, Bernkastel and Trier.

Much of Rick's advice for the Rhine and Mosel is unhelpful and/or incomplete/out-of-date, IMHO. Online resources are your friend.

Any stay in Boppard includes train tickets for that region. (Edit... thanks for the correction below.) You could radiate out from Boppard on various day trips with free transport. Note that going out of this odd shaped region requires additional fare.

We based ourselves out of Trier for two nights and it was worth it. It made a day trip to Luxembourg very easy. I didn't know what to expect but we were blown away with Luxembourg and would absolutely return. Trier itself can be covered in an afternoon.

I enjoyed time in Cologne and Bonn but we have family heritage in that area which made it memorable. Bonn has Beethoven, Cologne has the Dom. Either town can be done in a few hours in my opinion. Three full days is a bit of a stretch I think that could best be spent elsewhere.

Having done roughly your itinerary (we based out of Bacharach and Trier) in hindsight I'd do Boppard and Trier and venture out from there. We rented a car out of Koblenz for part of it and it was good and bad.

The car made it easy to get to those great Mosel towns like Bernkastel, Burg Eltz and Beilstein. Plus the drive is spectacular. On the downside, the hassle of parking, especially in Trier, added logistical challenges. Trier back to Frankfurt is indeed a stretch, maybe train back the night before your flight and spend a night at an airport hotel? For us, having the car added a lot of hassle. Was it worth it? Maybe? I'd go 50/50. Maybe just rent a car for the Mosel part? We did a one way rental Koblenz to Frankfurt from Enterprise. There are plentiful taxis at the main train station in Koblenz to get you to Enterprise, about 12 euro if I remember.

Any stay in Boppard includes train tickets for that region, which goes
all the way to Trier.

Yes - and no.

All Boppard establishments - hotels, apartments, B&B's - offer this multi-day transit pass to their guests upon check-in:

https://www.vrminfo.de/fileadmin/data_vrminfo/PDF/Gaesteticket/Infoflyer_Gaesteticket_englisch_2022.pdf

But as the train-line map makes clear, Trier does not lie within the VRM zone of eligible destinations for this pass.

Cochem: day trips by public transport are not difficult. For Beilstein (no train station, not a good base town for train users) the cruise boats from Cochem are the way to go... it's a lovely 1-hr float each way. ALSO: the same VRM pass you got in Boppard is available in Cochem from certain participating innkeepers. You can find Cochem's on the master list of those participants; look under the "Ort" column on the 2nd page to find their names:

https://www.vrminfo.de/fileadmin/data_vrminfo/PDF/Gaesteticket/VRM-Gaesteticketvertraege_April_24.pdf

Without the Guest Ticket, you will probably find this day ticket handy for getting around to places like Trier, Bernkastel, Traben-Trarbach and others:

https://www.vrminfo.de/en/tickets/tickets/leisure-tickets/rheinland-pfalz-ticket/

If Boppard will be your first base town... you might want to include a cruise through the most scenic part on the way; take the train from FRA to Bingen and board a cruise boat to St. Goar. From there, it's a 10-minute train ride to Boppard.

At the end of your trip: I'd recommend a day and a night in Mainz, just 25 minutes from FRA by direct train.

Koblenz can be a good base of operations for day trips along both rivers.

There are “cuter” towns - and Koblenz is really more of a small city - but I nonetheless enjoyed it for the practicalities. Plenty of dinner options after a long day of activities. Efficient train connections around the area. Groceries for snacks or a picnic lunch. And although the city itself isn’t a notably major tourist destination itself, I still enjoyed an afternoon walk around the town and along the rivers.

Frankfurt is probably too far south from where you want to be. Cologne or Trier would be other options for larger cities - I didn’t visit Trier but have heard good things.

I’d rent a car for the Rhine part. It’s gonna make your short time a lot more efficient.
Base in your choice of Boppard or Bachrach (Rhine, but more right sized) or Beilstein (Mosel, small & quaint) if you don’t mind driving 40ish minutes to the Rhine for daytrips. Beilstein does put you closer to Burg Eltz. I’d budget a jet lag/travel day + 4 days

Then on the 6th, drop the car at Koblenz and take an afternoon train to Nuremberg. That’s your new base for the 7th 8th & maybe the night if the 9th; depending on how early your flight is. You can get a Nuremberg train to the Frankfurt airport in < 3 hrs so you could stay in Nuremberg if your flight wasn’t AM, otherwise maybe spend the night if the 9th in or near Frankfurt.

Look for a weekend wine festival in one of the towns on the Rhine and Mosel rivers. Usually they are in late August or September, but there may be some late ones in early October. Always a fun time.