The new German trains (ICE trains) are just beautiful, and they're almost as fast as the airplanes (368km/ hour)! They are very modern, have lots of legroom, and fantastic dining. You don't hear the click-clack sound in them; they seem to soar over the tracks. They even have movies at each seat, like in an airplane...only you have so much more room.
Here is a link with pictures:
ICE

Here is a link in English

Intercityexpress

What a wonderful present to give your nieces! That's something they will remember for the rest of their lives, that's for sure.