Private Day Tripand tour to Cesky Krumlov from Prague

Go online to ckumlov.info and then click on English. Click on "travel and transport," and then click on taxi.
A number of CK shuttle bus companies are listed. They travel far and wide hauling people around the region, including Salzburg, Vienna, Prague and sometimes even Budapest.

It depends on your interests, but if I had to choose between the two, a day trip to Terezin would win hands down. We did our Terezin tour with Pavel Batel and he is an amazing guide who is knowledgeable and passionate about the subject. One of the best tours we've ever taken. http://terezin-private-tours.com/?page_type=article&page=1 We found Cesky Krumlov to be highly commercialized and it's packed with day trippers and souvenir shops. In my opinion, you don't really need a tour guide to visit the city, only transportation to get you there. Look at CZ Shuttle for options from Prague. http://www.czshuttle.cz/

With only three days, you may not want to do a day trip at all. If you want to see Terezin, that's unique, so you should definitely do that. I agree that a day trip to Cesky Krumlov (three hours each way) is not a good use of a short time in Prague.

"Amazing day trip" is not the way that I would describe a visit to Terezin. I tend to describe it to clients as a "worthwhile" place to visit, but it is not somewhere that I expect people to enjoy visiting.

Marcus,
If you read carefully, I described Pavel as "an amazing guide". The post did not say that Terezin is "amazing". It is intense and thought provoking, especially to those who have an interest in history.

Thanks for your suggestions. I think I agree that a long day trip is not the best use of our time as there seems to be quite a lot to see in Prague itself. I think we will visit Terezin.