I just finished figuring up how much we spent on our 7 night Eastern on the Fantasy. I always do this after trips as it helps us to budget more accurately for our next one. Here's a list of everything we spent money on related to the trip...
Cruise Fare
Trip Insurance
Airfare
Airport Parking
Tips for Porters at PC
Pre-Trip Expenses (clothes, nails done, shoes)
Boarding for Pets
Airline Luggage Fees
Airport Food
(my in-laws live near PC so we don't incur transfer fees from the airport to PC or hotel costs)
Actual Onboard Expenses we incurred:
Liquor
Mixology class
Arcade
Bingo
Coffee from Vista Cafe
Internet
Laundry/Dry Cleaning
Souvenirs
Palo Brunch plus tip
Pictures from Shutters
Automatic Gratuities
Extra Gratuities for Excellent Service
Tips for Room Service
Bibbidi Bobbidi Boutique (just on Fantasy so you wouldn't have this charge)
Snacks for shows in WDT
Excursions through
DCL
Tips for parasailing on CC
Deposit for next cruise
We also did a non-DCL excursion so budgeted for that as well as a tip for the tour guide.
Also budget for souvenirs bought off the ship.
I'm not going to list what we spent on each item b/c it varies so much by what your interests are. But for us, our biggest on-board expenses were... DCL parasailing excursion, liquor (we enjoyed Europa on the Fantasy and my DH always had 2 drinks with dinner each night), souvenirs and Bingo.
Another big expense you could incur is for spa services, but we didn't do that this trip.