Heading out to a 2 week Viking river cruise next week. Amsterdam to Budapest. Canon 70D with several lenses. Any suugestions on which lenses to take and special places for photos?
Viking cruise is great! We took that cruise a couple years ago and got lucky to be on board Viking Baldur on its maiden voyage. Guess what? Wine flowed without freely, we had Karl Heinz-Zwanzleitner (head chef - known in Europe), great staff, and great excursions. https://www.travelagewest.com/Travel/River-Cruise/7-Top-Chefs-on-the-European-Rivers
I only had my Panasonic ZS50 with me at that time. But took decent photos. Knowing more about digital cameras now, for your trip, take an extra reach lens (e.g., Tamron 18-400 or equivalent) and a fast lens for indoor shooting or excursions with low light such as inside castles, cathedrals, etc. You asked for photo ops - here they are:
Amsterdam - if you have time (own your own): 1) take the boat to travel the canals, 2) Van Gogh Museum, and 3) Anne Franks House. Be mindful of the boats schedule for last trip back to the boat. You will most likely visit Kinderdijk - windmills (through Viking). Back to the ship. Both outdoor and indoor photo ops.
Cologne (Germany) - Cologne Cathedral (Big) and the square where people do their business or public entertainment. Cologne perfume, etc. May visit a public market with the chef. Back to the ship. Mostly outdoor photo ops but some indoor.
Koblenz (Germany) - visit the Marksburg Castle along the Rhine. Take the bus to go there. Viking staff will go with the tour. Tour guide will give history of the castle with focus on the military tools and ways the castle was defended; several rooms of the castle. Wear your wireless speaker all the time. Beautiful scenery. They'll give you time to take pictures. Back to the ship for great food/drinks. Ship sails to next destination. Along the way, lots of castles, churches, beautiful houses, locks and more locks. They'll call your attention to the legend of Lorelei.
You may see the birthplace of the printing press (Mainz) you'll probably arrive in the evening (on your own). Bring your fast lens, here.
To Miltenberg (stroll the town). Cameras ready: Gives you a sense of the medieval, romantic life in the 16th and 17th centuries.
To Wurzberg - great architectures; for the sculptures in you, home to the world's greatest collection of medieval master of wood sculptor, Remenschneider.
To Rothenburg - "Romantic Road." Stroll the town. You'll probably have lunch here in one of the German restaurants. Wurzburg Residenz Palace will overwhelm you. Opulence on display. Get your camera ready. I think there is enough light indoor. But, have that fast lens on hand.
To Bamberg - try the German smoked beer (Rauchbier). Used to be the center of the Holy Roman Empire (Emperor Heinrich II). Stroll the town. Band music and dancers probably performing on stage. Lively place. Mostly outdoor photo ops.
To Nuremberg - Events that almost changed how we live. Hitler's rally speech ground (they'll take you there - ready with your camera). Claus Graf Staffenberg. Judgment at Nuremberg. Also, architectural splendors. Mostly outdoor photo ops.
To Regensberg - stroll the town. Mostly outdoor photo ops.
To Passau - Meeting of the 3 rivers. St. Stephen Cathedral big organ will leave in awe. (Outdoor and indoor photo ops)
To Melk - the main event: Melk Abbey. Camera ready (outdoor and indoor). This place is yuuge.
To Melk - small Austrian along the Danube river.
To Vienna - mostly Mozart. St Stephen's Cathedral. Try a tasty pie or specialty in one of the cafes. Lot's of outdoor photo ops.
To Durnstein, Austria - mostly outdoor photo ops. Claim to fame: King Richard I the Lionheart of England was held captive.
To Bratislava - mostly outdoor photo ops.
To Budapest - both indoor and outdoor photo ops (excursion). Camera ready for the nighttime sail to the Hungarian Parliament. Long and fast lens ready.
If you are extending to Prague, good for you. Beautiful city. Lots of outdoor photo ops.
Hope the helps.