I'll fly to Amsterdam next April and, after that, I'd like to visit Poland, Estonia, Latvia and Lithuania. I'll be with a friend and we would like to know if we could do this on our own in 15 days - or we'd better take a guided tour. I thought I could fly Amsterdam/Tallin, then take a bus (Eurolines or Ecolines) to Riga and Vilnius, then to Warsaw and fly back to Amsterdam. Or should I do the opposite way, concerning fares and prices? I like to walk around the cities and someone told me that Vilnius is a small town (2 days would be enough). Riga and Tallin are larger cities, as well as Warsaw. How many daus do you suggest me for any of the cities? And what about travelling by bus? Thank you!!