Best luggage for trip???

Take the smallest luggage you can jam your "stuff" into. You need to hop off trains and manage steep stairs between train platforms, and do it quickly! My mode is a two- wheeled roller bag and a backpack for layers, guidebooks, and snacks. I don't carry a purse, I use a travel vest with inside zipper pockets for my wallet and sunglasses, and a Bandolier phone case with neck strap.
There is much discussion here between two wheeled vs four wheeled suitcases. Again, I feel two wheeled suitcases handle cobblestones better.
Have a memorable trip, thinking of your grandmother. Safe travels!

You can use backpacks or roller bags or even spinner bags, but really it is up to you and your level of comfort. I prefer spinner bags but I'm 68 and like being able to leisurely move it along at the airport. And I have never had a problem taking it over cobblestones. :-) But there are others here who prefer roller bags, and some that like having backpacks.

One of the regular members here has been using a Cotopaxi Allpa 35L backpack, which has it's own compartments and opens like a clamshell. It's a very nice bag (I own it myself) and is very lightweight.

If you go to the Packing forum, you will find dozens of threads that discuss the various benefits of bags. https://community.ricksteves.com/travel-forum/packing

For hostels and train travel I would totally do backpacks, but that's just me. I don't have any roller luggage. Just backpacks of various sizes and duffel bags.

I use the RS Rolling Carry-On and a lightweight nylon tote with a trolley strap. My purse is a very small Travelon crossbody, my moneybelt is a Stashbandz. In the bottom of my tote I carry a 20L Eddie Bauer day pack for days I need to carry more.
If your back can handle a larger backpack you can use that instead of a rolling suitcase. The tote would be optional if a small backpack can double as your personal item.
At 73 I have no problems getting on and off trains and up/down stairs. Packing light is the key (and my challenge).

Your trip sounds exciting. What a great family experience. Enjoy!

The Best luggage to take is the one that is best for you.

If you have never traveled with a Backpack, borrow one, fill it to the approximate weight it would be for your trip, and take a lenghtly walk. Make sure you go up and down steps. See how you like it.

The one thing I will suggest.....which bag you choose, make it as light as possible. You will have to carry it, lug it, drag it, lift it and more.

My experience is that for train travel rolling duffel bags are great. Don't get a spinner.
Advantages of such a style of bag:

• The length to width proportions are better suitable to being stowable in the overhead racks.
• Larger wheels deal better with uneven pavement in old cities.
• They usually have a strong skid plate between the wheels, which makes it possible to just drag them up stairs, in the trains etc...

I have one, and I have walked kms with it.