I am a numbers girl, so I broke out my expenses much like I would my personal finances... by fixed expenses and discretionary expenses to come up with a range that was "bare bones" and one that was more realistic. My only suggestion is to NOT include a line for "pre-cruise expenses" such as a new bathing suit.
If your "bottom line" DH is anything like mine, these would not be approved.
Fixed
Cost of cruise
Flight/luggage/transportation to/from airport (home and away)
Hotel if staying night before/after
Gratuities
Discretionary
DCL Port Adventures
Other port excursions, including transportation/meals if necessary
Speciality drinks
Palo/Remy
Spa/Rainforest Room pass
Bingo**
As a comparison, my Fixed expenses for 2 adults, 7 night cruise (inside cabin), coming from the West coast and staying the night before, came to about $2,850. The range for Discretionary ranged from $100-$1,000, and then we decided what was a priority and what was not. So for my "bottom line" DH, I gave him a range of $3,000 to $4,000.
**Bingo was not something I had planned on, and yet by the end of the cruise it was one of our largest onboard expenses! DH really enjoyed playing, so we hit EVERY session. To be fair, we did receive a $500 OBC from signing up for DVC, so he felt like he had some play money. Next time, there will be a strictly adhered to budget.