I am planning to do a backpacking tour to the mentioned countries. I will start from Warsaw, and since my final destionation is Kraków, I want to go to TAL from Warsaw, and then go south, visiting Estonia, Latvia, Lithuania and Poland.

First, which cities do you recommend in the Baltics(of course I will visit the capitals, but I want to experience the countryside too)?

And what is the easiest way to get from Warsaw to Tallinn? Are there any railways, or only buses?