Traveling to Berlin from a Cruise Ship Port Warnemunde

When we went we hired a private guide who took us to Rostock, which was part of east Germany. The train ride was very short. We had a lovely day. Look under toursbylocals.Com on the banner in the right they advertise cruise ship excursions.
Berlin needs at least a week to appreciate.

No it's not worth it because you can easily drive to Berlin all by yourself without a guide. Furthermore, Berlin deserves to visit for a few days.

Warnemünde is an old fishing village and it is worth visiting. Stroll through Alexandrinenstrasse and imagine what it was like when the fishermen lived and worked there. There is also a small museum you could visit.
Enjoy a fish sandwich from one of the cutters on the old river (Alter Strom).
Climb up the lighthouse and enjoy the view - you can easily miss out the ugly Neptun Hotel (a relic from the GDR).
Walk along the mole to the port entrance and simply enjoy the view of the incoming ships for a while.
And it shouldn't be unmentioned that Warnemünde has the widest sandy beach on the German Baltic Sea coast. Maybe you just want to spend a day at the beach?
There is also the possibility to book a harbor tour including Rostock and Warnemünde. Rostock port is a huge operating seaport.

You can take the S-Bahn from Warnemünde to Rostock and visit the city center with a guide.

What I would definitely visit is Bad Doberan. Its Minster is mind blowing: https://www.muenster-doberan.de/index.php/en/welcome
Bad Doberan and neighboring Heiligendamm (not worth visiting) were very popular with the German imperial family and therefore they had a summer residence there.
What's really fun is to take the Molli Steam Train from Bad Doberan to the village of Kühlungsborn (a typical seaside resort) and back.

See also:
https://community.ricksteves.com/travel-forum/germany/12-hours-in-warnemunde

That's a lot of money and travel time for a very limited visit to Berlin itself. I liked Berlin a lot on a separate trip, but on the cruise we took a cruise-line-provided bus to Rostock and enjoyed a day there -- nice medieval church with an astronomical clock, other attractive buildings in a largely restored, pedestrian-friendly downtown. We wanted to see the Stasi museum there but it had closed, don't know whether that was temporary or permanent. We didn't get to Warnemunde because our ship docked in Rostock.

Save Berlin for when you can spend at least several days there. Spend your shore time in Rostock or Warnemunde or another place nearby.

I would do an independent trip to Wismar and the Molli, and give myself time to explore Warnemunde.
$425 for a day on the Coach is daylight robbery.
In 2019 I thought £100 for the same excursion to Berlin couldn't be justified- 4x that is unbelievable.

Yes, it is absolutely worth it for Berlin, without a question. Especially if you may not have a chance to visit the city/area again. It is a good idea to go with the cruise ship for a longer tour farther east from the port.

The price is actually surprisingly low, compared to other far flung full day tours from ships in other parts of the world. Since it’s fully guided you can relax, hopefully have some good meals on the way as well.

I will add that, if you can easily see Berlin on another occasion, and for a longer time, then of course do that!

That is highway robbery, considering the price of a RT bus or train ticket. And out of that 11 hours, you'll spend a minimum of 5 hours (train) or 7 hours (bus) just getting there and back. No, it certainly isn't worth while.

Knowing how close the cruise port is to the Railway Station, and that there is a train into Rostock every 10 to 15 minutes (sometimes every 7 1/2 minutes) if my heart was totally set on Berlin, I would take the train for the 3 hour journey for between 22 Euro and 45 Euro each way, then a HoHo bus in Berlin.
I personally would relish that far more than the long bus ride.
The cruise lines sell their excursions on the fear factor. On DB the chance of my missing the ship is very, very low. We have cell phones nowadays. If the very worst happened I can call the ship. If I can't get to the next port of call in the Baltic by other means (I would have a reserve plan for that) then it's time for me to give up travelling.
But I would get either a city transit ticket or a German Lander train ticket and explore the local area, not a distant city.

Please let us know what you decide to do. We are on a cruise that starts next year and stops there. We have been to Berlin twice so we are going to stay in the local area and try to see a castle/palace.

We have been to Berlin twice so we are going to stay in the local area and try to see a castle/palace.

I don't know what you expect but it won't be quite like the castles on the rhine or any well-known royal palaces. But for me the most beautiful is 'Schloß Schwerin'.

https://entdecke-deutschland.de/en/bundeslaender/mecklenburg-vorpommern/the-most-beautiful-castles-of-mecklenburg-vorpommern/

Mignon's advice is perfect. I enjoyed reading it as it matched my experience.
The trip to Berlin is not worth it- it is a very long, tiring day and most of the day you are driving by the sites! Please, go back to Berlin when you have at least 5 days.
I have docked from a cruise in the area three times and used both a ship excursion and taken trains myself( very easy and quite close to your pier) - and also spent a few hours on the beautiful beach with chairs to rent. Enjoy a lowkey day anywhere in the area there.
You might consider joining the 'roll call' on Cruise Critic where you may find other cruisers on small private tours to your liking.