Beilstein or Bacharach?

They are both pretty, Beilstein is quieter.

We preferred the Mosel to the Rhine in general. We prefer a quieter, less busy feel. If you go with the Mosel, visit Burg Eltz. The best castle experience one can have, in our opinion. Beilstein is very small and very quiet. Maybe Cochem or nearby would be of interest. We stayed just across the Mosel from Cochem in Valwig. If I were to pick between your two, it would be Beilstein.

Paul

The Mosel is more picturesque, quiet, and less industrial than the Rhine.
We stayed in Bacharach and enjoyed the castles on the Rhine, as well as the superb cheese soup at Altes Haus - built in 1368 !
But we also stayed in Beilstein, and you can walk the town in 15 minutes. So it was much more quiet.
I, too, hope that you plan to park in Moselkern and hike the trail up to Burg Eltz - delightful and easy.

Which river do you plan to explore? Rhine or Mosel? Both? You might need another night for this area. If it's only the Mosel...

Beilstein is microscopic. IMO good for most people of my advanced age, or maybe honeymooners. But probably too small to stay in for more than a night for most. This is it.

Cochem on the other hand is a real town, a small one but large enough that you could wander around for a couple of hours to explore its nooks and crannies. There is a wider variety of places to eat/drink and of accommodations. The chairlift ride, the castle tour, the water park, the mustard mill... there's more to see and do for families here than anywhere else, and Burg Eltz is close by.
Cochem's market square

I would stay in the old town zone where the market square is.
Upscale accommodations
Inexpensive rooms at the zum Fröhlichen Weinberg
Haus Andreas
Eateries
Chairlift

A boat ride to Beilstein from Cochem is fun and takes 1 hour each way.

On the Rhine, Boppard, St. Goar (Rheinfels Castle right in town) or Oberwesel should be considered in addition to Bacharach. All are on the same side of the river and each has its own charm. Bacharach has a reputation for train noise - read the reviews carefully.

If you are visiting both rivers, Boppard, with the most hotel/dining choices and a few diversions, has the best location.

Someone mentioned industry on the Rhine. This is visible near Koblenz but you won't see this sort of thing south of Braubach as far as Bingen.

River scene in Boppard

Thank you so much everyone. I think we would explore whatever river we choose to stay on, rather than attempt both. I was at Burg Elz many years ago but my children have never been there. I am attracted to the "quaintness" of Beilstein, but the abundance of River boats available on the Rhine are also a draw; for example, if we rented bikes and biked one way, boating back the other way. So I think it's between Bacharach and doing something like that, and the Mosel and Burg Elz. Does that sound right - maybe I'm missing some opportunities? Sounds like there are boats from Beilstein as well...

I must admit I am also very intrigued by the "wine carousel" I have heard about at Bastien's Weingut zum Grüner Baum, and they're would be no driving after that! But I have also heard that the terrace at Hotel Haus Lipmann in Beilstein is very nice, so I am in a real decision quandry.

"...for example, if we rented bikes and biked one way, boating back the other way."

I've never tried this with bikes. If sold on biking I'd consider the quieter Mosel area and research the route. On both rivers, some paths are dedicated - elsewhere you share with cars.

It's very easy to chew up your time doing a Rhine cruise. The most scenic part is Bingen to St. Goar (1.5 hours on the boat in this direction.) Bacharach lies right in the middle. So if staying in Bacharach, the most efficient plan is to first catch a train to Bingen, then cruise north to St. Goar (where you maybe visit Rheinfels Castle) then return by another train (10 minutes) to Bacharach, stopping on the way in the fetching town of Oberwesel, perhaps for a walk around the town wall.

Staying in St. Goar would simplify the above - one train ride to Bingen (stopover in Oberwesel if you wish,) one cruise back to St.Goar. And Rheinfels is right there in town so you can see it anytime.

If you reverse the cruise direction (St. Goar - Bingen) you will end up spending nearly 3 hours on the boat to see the same scenery (very strong current.) Round trip boat plans mean spending most of the day on the boat and repeating the same scenery.

Thank you for that helpful reply. I didn't realize the current would make that much of a difference, and that it could eat up that much time. I am beginning to lean toward the Mosel and like the Burg Elz hike idea. So you park in Moselkern - is there an option to get back to Moselkern where you don't have to retrace your steps?

On weekends in the summer there is also a bus run from Treis-Karden, Hatzenport, and Moselkern to the parking lot above Burg Eltz. You can find it on the German Rail schedule website.

Russ had some very good information,we stayed in Beilstein at the Hotel Gute Quelle,very nice room with balcony and included breakfast and they also serve traditional German dinners and the owner was great and there is parking within walking distance.The ferry dock is 100 yards from the hotel where you can go to Cochem and walk the town and tour the castle on the hill.
Mike

Thank you so much for your replies. We have decided on Beilstein and have booked the Hotel Haus Lipmann for two nights. I think we will do the Burg Elz hike to the castle and bus back. Can't wait!!