One other thing. If there are specialty restaurants onboard the ship you choose, those will have a cover charge. An example is on Royal Caribbean ships, they have Chop's Grill and Portofino. I believe for those the cover charge is $20 per person, but supposedly it is well worth it. I haven't tried those. What I have tried, is Johnny Rockets, another restaurant onboard select Royal Caribbean ships. That is a $4.95 cover charge, all you can eat. Drinks are extra.
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)