Have done 4 river cruises Amazon,Nile, Volga /Neva & Lake nasser. Biggest roll we had about 2mm and pitched about the same. Cabins could have been bigger.Quite a change being a passenger. Dont forget opera starts at 19.00 sharp.
I visited Prague earlier in the year, my main recommendation is take a camera, the place is stunning especially Charles Bridge which leads to the castle area, if you visit the castle/parliament area get a guided tour or you will miss Wenceslas's coffin, there is also a solid silver & glass coffin in the St Vitus cathederal of one of Prague martyrs. visit The astronomical clock and the church of "Our Lady before Tyn", (lovely by night), in the Old Town Sq, also try the local bars and restaurants where locals eat & drink, very cheap and excellent quality, also very friendly, Wenceslas Sq is full of history, the Metro system is cheap, clean and efficient, and the trams are more fun than using an "obchody".
Have a good time.
Steve (from Sunderland).
Went to Prague earlier this year, wonderful place. Would suggest taking one of the guided walks ealy in your visit then retrace if you see anything you really liked. I was very taken with the Municipal House. Very art deco, especially the American Bar and the restuarant but whole place just totally art deco. Tube system very good, easy to use and cheap.. Have a good time
Was in Prague about 10 years ago. Beautiful city, nice friendly people, but--- watch for pickpockets. Gypsies ( are we allowed to say that ? ) abounded at the Fisherman's Bastion, a place well worth a visit. Have a great time, don't miss the Charles' Bridge.
Incidentally, regarding river cruises, I did one on the Rhine and Moselle a couple of months ago. The scenery and the weather was wonderful. The cruiser was the " Fortuna " which was absolutely disgusting. It must have been used by the SS for R n R during the war. Should have been sunk 50 years ago.