Train From Berlin To Krakow Vienna, Budapest, Krakow, Berlin By Rail ?

Vienna, Budapest, Krakow, Berlin by rail ? - train from berlin to krakow

I am planning a trip to Central and Eastern Europe next year. I expect the plane to Vienna and traveling by train to Budapest, Krakow and Berlin. Any advice, whether it is better to buy a rail pass or point-to-point have tickets? Since the lines are long enough, I prefer to travel by rail bed. Trains railpass cover the bed? I also welcome any other advice or suggestions, such as accommodation or (cheap!) Things to see and do. I am planning a trip of 3 weeks.