Looking at Paris to Praque. Which line?

[cjsr]

A girlfriend and I are looking at a Paris to Praque or vice versa for next year. They must be popular as some are already sold out. Any ideas on which line is better? Also weather wise which time frame is best. First river cruise for both of us.

[cjsr]

I'm looking at the CIE cruises as they offer an excursion to a town in Germany I want to go back to. I know they are new to the cruise business. They are also using some of the same ships, the Amalergo, etc.

Thanks