Sodas and Alchol are extra. As well as some resturants on the ships. However the main dinning rooms and the snack grills and buffet lines are included in the cruise (and room sevice except for the tip). I agree with the beverage cards (on Carnival its called a Fun Fountain card) for the kids. Not too sure if it is worth it for adults unless you drink a lot of soda. The kid price for price for the card is less than for the adult (price depends on the length of the cruise) with the kid card for a week is about $27. The reason I'm not sure its worth it for the adults is that the cards are only good for glasses of soda, not bottled soda. Glasses run about $2 each and I think a bottle runs $3. So for the adult price of $42 you can get roughly 22 glasses of soda. Unless its all you drink, it is going to be difficult to consume that much soda. Plus you need to bring the card everywhere you go (Not too bad but still....) Whereas if you pay as you go, you can get soda bottles and recap them to take them around with you.
Obviously its your call, but I wanted to explain it so you could make an informed choice.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013