All Day Itinerary - Cochem, Bernkastel, Trittenheim

You can use buses to get from Bernkastel-Kues to Trittenheim and back. It is the 333 bus and take 45 to 55 minutes. You can see the schedule at www.bahn.com. Also if you plug in Trittenheim to Cochem, you might see that taking the 333 bus to Trier Hbf and getting the train to Cochem from there.
Get a Rheinland-Pfalz ticket for 29 EUR for two people. Travel all day, but begin after 9 am.

Edit-If you can re-arrange your itinerary to be on the Mosel for the weekend, there are a couple of wine festivals in the area. These are always worth attending.

Brauneberg is on the river between Bernkastel-Kues and Trittenheim.
Fr., 22.09.2017 – So., 24.09.2017
Wein- und Straßenfest an der Nußbaumallee in Brauneberg

Neumagen-Dhron is the town immediately north of Trittenheim.
Fr., 22.09.2017 – So., 24.09.2017
Weinstraßenfest "Römerstraße" in Neumagen-Dhron

And with a R-P ticket, you can start your trip anytime Saturday or Sunday.
You can use a VRM ticket to travel to Burg Eltz. If a Saturday or Sunday, you can get a bus from Hatzenport to the Castle.

We really enjoyed Cochem, and I would think you could easily spend a day. The castle is very enjoyable, and the town itself is fun to explore. You can take a boat trip or bike ride on the Moselle also. I'm also not sure what there is in Trittenheim, but we are spending a night there on our bike tour next summer - so I guess I'll find out:) What I'm wondering is have you been to Trier before? I would put that a much higher priority than these smaller towns.

Dates are not flexible. I am sad to know I'l be missing some festivals. We'll likely be back next year (Munich/Moselle/Italy) if we find we like Moselle. Re Trittenheim: To be honest, I was told to stop there for Riesling. I would happily abandon if there is nothing there. We are staying in Cochem and have lots of things to hit in Bernkastel-Kues. Is Trier doable in addition all in one day?

Trier has enough sites to fill a day. We did it as a day trip from Cochem and really enjoyed it. If you limit the sights you hit in Trier you may be able to spend 3 or 4 hours there and have time to fit in another destination.

Riesling is up and down the valley, the hillsides along the river are covered with grape vines, and every little town has its home "brand", like Zeller Schwarze Katz in Zell.

There are places right in Cochem with wine rooms and wine gardens. The Haxel Winery (Weingut Haxel) has both - it's wine room is even called the "Rieslingstube" (Stube = room.) And like many Mosel wineries, it has rooms - with breakfast - as well as wine rooms. Maybe you'd enjoy staying at such a place.

http://haxel.de/?lang=en (you can find it on booking.com as well.)

Here's another such place in Cochem: http://www.weingut-rademacher.de/en/

Hmmm. Thank you for all the wonderful advice. We get to Cochem around 3pm Sunday. We can maybe explore Cochem Sunday night if everything doesn't close early. If so, revised itinerary:

Monday - Trier all day
Tuesday- Cochem early (Castle & Falcon show) then Bernkastel rest of the day.
Wednesday - Burg Elz in the morning and then more in Cochem Wednesday late afternoon/night (early 6 am train back to Munich on Thursday).

Does that sound more appropriate/doable?

Looks excellent to me!

Shops in Cochem will be closed (except for soviener shops) on Sunday but everything else will be open and not closing too early (restaurants and such usually only close one hour earlier on Sunday).

I stayed in Cochem for two nights and would not say that the city needs a full day to explore, even including the castle. We managed to see it in full arriving on a Friday afternoon and departing mid-morning Sunday, and that was with a day trip to Trier and a visit to Burg Eltz.