Planning itinerary for Europe trip from late December to early Feb - How does my itinerary look? Any suggestions?

This will be our first trip to Europe M28 & F27.

Is there any countries or cities you think are worth adding/removing from our itinerary? Pro's/cons?

We were also exploring other countries like Switzerland, Denmark, Sweden etc, however, they are quite costly & a bit out of the way in our itinerary. We would ideally prefer to get trains where we can.

*London, UK - 5 NIGHTS

*Edinburgh, Scotland - 3 NIGHTS

*Paris, France - 3 NIGHTS (considering cutting this & doing a day trip from London)

*Prague, Czech Republic - 3 NIGHTS

*Vienna, Austria - 4 NIGHTS

*Krakow, Poland - 3 NIGHTS

*Rome, Italy - 5 NIGHTS

*Florence, Italy - 3 NIGHTS

*Athens, Greece - 5 NIGHTS