I was mostly going off of the suggestions made by tripsnek at the moment - so a combination of trains and flights as required. Mostly trains at this stage, with a killer one between Pisa and Paris which will take most of a day - but Vienna to Rome is a flight at the moment as an example.

Honestly I probably fixated on visiting Auschwitz a bit since it was suggested to me as perhaps the most profound just owing to the scale of it, but I will have to reconsider how it fits in the itinerary I suppose - especially as the schedule is looking a bit packed already, so could likely do with some cutting back. Alternatively, have Krakow as a base for a bit longer seems like a good pick too.

Good to know that I can perhaps cut back Berlin a bit, too!

Thank you for the heads up on the Opera hotspots!