Valetta is a lovely city. Very old with a great deal of history. Took the open top bus tour which was a waste of money. Much better to explore Valetta on foot, or just jump on the local transport. Very cheap port.
Always a great city which we never tire off. The MSC excursions were very expensive but you have to go. Favourites sites are the Vatican...don't miss the museum, cistine chapel and the basilica. The Colosseum is unmissable also.