Rhine/Mosel 3 questions

1. Cochem would be more central to visit Burg Eltz and biking along the Mosel.

2. Train is very easy and they are frequent right from the airport train station.

3. To get to Munich, it is very easy to get trains to Munich.

Let me add, that you could travel by boat from Bingen to Boppard and go by train from there to Cochem or Trier. Also, to visit Burg Eltz, there are buses from train station along the Mosel during the weekend. During the week, you would have to hike a couple of miles uphill from Moselkern train station. Otherwise, you could rent a car for a day and drive to the parking lot above the castle.

The region is well served by train. Unless you want a car for more extensive exploring, you can get around easily by train.

Bacharach is central-ish to the middle Rhine, and Cochem is central to the Mosel; two different rivers that intersect at Koblenz, which is also where you change trains from one area to the other. Staying in either Bacharach or Cochem and wanting to visit the other river will require 40-60 minutes of train ride.

Don't forget Marksburg castle along the Rhine. Marks burg and Burg Elz are RS' favorites, and having visited both, they are a great combination and study in different styles. I preferred Marksburg, in part bc the tour allowed you to walk around more where Burg Elz' tour was more like visiting a protected museum.

Maybe stay in Cochem two nights and Bacharach for one. I think Bacharach is a more straightforward departure for Munich, BUT not sure, so once you've looked at train routes and times, you can asses which town is the better departure for Munich and stay there your last night.

I would train to Munich, but again, different travelers prefer different things

With 3 nights I would stay in one location. 3 nights is really only 2 full days. I don't see how you can possibly fit all that into 2 full days unless you will be arriving in the morning of the 1st day. Trier deserves a day, the Mosel at least a day - especially if you want to visit burg eltz. The Rhine also needs at least a full day. If it were me I would pick one or the other (the Rhine or the Mosel). We stayed in Cochem for 3 nights without going to Burg Eltz and stayed very busy - with renting bikes and riding between Cochem and Beilstein, and a day trip to Trier. I've also spent 2 nights on the Rhine in Bacharach (with a day trip to Burg Eltz on a different trip.

I would take the train to Munich. No need for a car.

Two of your three suggested venues are bicycling on the Mosel and visiting Burg Eltz. Cochem would be ideal as a base (if you want a smaller town, try Treis-Karden).

If you want to make a trip to Trier, it's about an hour by train from Cochem.

The trip from FRA to Cochem is about 2h15 by regional train. It will cost almost 39 euro for two - 4,90 each for local tickets to Mainz Hbf and 29 euro for a Rheinland-Pfalz ticket from there to Cochem. You could even get off the train at Bingen-Stadt and take the ship to St. Goar (you'll get a 20% discount on the ship ticket by showing your train ticket), then resume travel by train from St. Goar to Cochem.

If you go from Cochem to Munich, you can get an advance purchase SparPreis (Savings Fare) ticket all the way, using an IC and an ICE in under 6 hours for 29,20 euro per person.

Bacharach - Trier one way = 2 hrs 10 minutes or 2 hrs. 40 minutes depending on which trains you catch.

You can narrow your area of travel by omitting Trier (which is probably a good idea unless you are seriously interested in the area's Roman history.) Then it's Bacharach - Cochem in 1 hr. 20 minutes (or 1 hr. 50 minutes.) Moselkern station (for the walk to Eltz) would be closer.

But Bacharach is not central to your area of travel.

You should consider Boppard as a base town for both rivers. This is a place Rick very wrongly overlooks. It's a great little town with lots of wining/dining/lodging options and much more central...

Boppard to Cochem = 1 hour
Boppard to Bacharach = 20 min.
Boppard to St. Goar (Rheinfels Castle) = 10 min.
Boppard to Bingen (best starting point for a cruise) = 30 minutes

From Boppard you could in a single day visit St. Goar and Bacharach AND proceed to Bingen for a late afternoon Rhine cruise back to Boppard (it's very convenient to have your hotel where the cruise ends, btw.) Then spend a second long day doing Eltz and Cochem - and still get back to Boppard. That leaves you some of one day - the first one probably - to see Boppard itself...

Riverfront
Chairlift
Gedeonseck Terrace
Old town, market square
Old town, historic buildings

Nice restaurants and wineries too:
https://upload.wikimedia.org/wikipedia/commons/9/97/Boppard_Weinhaus_R%C3%B6merburg.JPG
http://www.deutschlandgourmet.info/bilder/gross/5710-Restaurant-Weinhaus-Heilig-Grab-Boppard.jpg

And if you can somehow fit in some biking, there are places you can do this near Boppard... This shot was taken on a bike path on the Boppard side of the river just across from Marksburg Castle, a few miles north of Boppard in the town of Brey, I believe:

http://www.der-takt.de/typo3temp/_processed_/csm_RS4284_rpt-2010-rad-rheintal-057-brey__blick_auf_marksburg__rheinr_Dominik_Ketz___Rheinland-Pfalz_Tourismus_GmbH_13151d4098.jpg

And given that you're headed to Munich, it will take less time from Boppard than from Trier or Cochem.

Thanks everyone for your recommendations. Lots of great information that we will use!

No one has commented on the ease of a car. Last summer we had a rental car and easily drove from Mainz where we had been staying for a few days to beautiful Bacharach for 2 nights. In one full day we drove along the Rhine towards Koblenz, then headed on the Mosel towards Cochem and Beilstein. Lots of stops along the way including lunch and tour at Burg Eltz and ice cream in Beilstein. Nice drive back to Bacharach through the countryside ended our day. Biking along the Mosel near Cochem/ Beilstein would be lovely. You could just get a rental car at the Frankfort airport. The roads in Germany are amazing.