With the amount of drinking that you stated, I would guess at the $1300 range. That estimate includes auto-tips, drinks, pictures (at least 4), excursions for three ports of call and spa trips (massage and hair appointments.) And maybe a trip or two to the Supper Club.
Tips are easy to calculate, drinks depend on the choice of wine for dinner. If you get a bottle, they can re-cork it and have it waiting for the next night or two depending on how much of it you drink. So figure 2 to 3 bottles at an average of $40 a bottle. A bucket of beer runs $25??? (Its been a couple of years since I ordered it by the bucket.) Then a phoo phoo drink is $6 or so. Pictures run about $29 for a couple of 5 x7 with album and I think $15 each by themselves. A massage goes for about $125 and an "up do" for the girls hair is about $40. Depending on the excursion, you can spend $60 to $200 a person ($200 for dolphin encounters) so you can average those out to be about $100 or so pp) And supper club on CCL run $25 pp I think. Use those numbers and you can take a pretty good swag at what your account is going to be.
================================================== ========== 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
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013