The food in the main dining rooms are covered as well as some of the other eateries on board. Each ship/line has a line of "specialty" restaurants which do have an addtional cover charge. Keep in mind that charge of $20 - $30 does not begin to cover the quality of the meal you will receive. We make sure to book at least ONE meal there - plan to spend at least 2.5 hours for that meal alone as each dish is prepared JUST for you and of course the service it totally marvelous!
You will also pay for any alcohol or Softdrinks (sodas) which will be charged to your cruise card. You have the option of purchasing either the Drink Tickets. I think they are 4 alcoholic for like $21 (tip included) and 4 softdrink for $8?