As far the dancing is concerned, I recommend Costa, too. A lot of people say that Cunard is the only option. I never tried it because they are a lot more expensive. (Higher base price + you spend much more on drinks.) Costa has always 5 hrs of dancing on at least 2 good dance floors plus a few smaller venues. Always live music, a rich selection of dance styles, intermixed with some group dancing and alternative activities. What is important is the ship selection. I started on Costa Serena, which is by chance probably the best Costa ship for dancing. Unfortunately it is not more accessible for Europeans as it sails for Asian market - same as a few other "dancing" Costa ships. In general larger ships should offer better dancing; also avoid "neo" ships.