I would like to visit central Europe and head back to Paris in late spring (Last week or April, first week of May). I am trying to get my itinerary together and make some decisions. I found cheap flights ($500 return) with open jaw options to or from Berlin and Paris. I just got back from Paris in September but I fell in love and want to experience it in the spring. That means I am not bogged down with having to spend a large amount of days there. 2-3 full days would be enough for this trip. Here are the other cities I would like to explore but I'm not sure how doable this would be.
Berlin
Prague
Vienna
Lucerne or Bern
Paris
I will have 12 days (does not include arrival and departure days). Should I do this entire trip via train or have flights mixed in? Switzerland was added if I made this a train only trip I could stop over in between Vienna and Paris.. I am skeptical about spending too many days in Berlin as a recent trip to Italy reminded me that I prefer walkable over larger cities (think Florence vs Rome) Any suggestions?