I am plannig a trip that will includes four days in Prague and then a flight to the greek islands for 14 days. During my four days in Prague, I would like to make a day trip to either Berlin or Viena or both. What are some recomendations? Should I rent a car or take the train?

>I am plannig a trip that will includes four days in Prague and then a flight to the greek islands for 14 days. During my four days in Prague, I would like to make a day trip to either Berlin or Viena or both. What are some recomendations? Should I rent a car or take the train?

Neither Berlin nor Vienna is within day trip destination from Prague, unless you have a private jet.

If you consider getting to Vienna or Berlin from Prague for some more extended period of time, take the train - renting a car never makes sense just to get from city to city.

The train will take about 5.5 hours from Prague to Berlin and at least that long to Vienna.
With four days in Prague you'll find plenty to keep you occupied IMO without leaving the city.

>The train will take about 5.5 hours from Prague to Berlin and at least that long to Vienna.

Well, it's rather 4.5 h to Berlin and just under 4 h to Vienna, but nevertheless not a daytrip distance.

Prague to Vienna is 194 miles.Not really a day trip. But the two cities do compliment each other very well. Why not two days in each. The drive is very easy and interesting.

Dresden might be within reach for a day trip, and its most important sights can be done in one day.

Either one is too far for a day trip in which you can reasonably see much of anything. Good only if you're a "cross it off the list" traveler.