The buying airfare part is the most stressful to me
This is the first time we've done air on our own. We drive when we sail from Port Canaveral, and our other cruises not from Port Canaveral, we've done better with
DCL airfare than booking on our own (or at least even by the time you factor in extra insurance, ground transportation, etc.). Our TA is removing the air portion from our reservation today so we'll get the new "balance due" which will be significantly less

At that point I'll be able to determine exactly how much we've saved (and really, repurposed towards another part of this vacation). She did tell me we have a substantial on board credit which I need to remember in terms of figuring out the rest of our vacation budget.
Speaking of vacation budget, you'd think I know all this but I want to make sure I'm not forgetting anything:
Pre-cruise transportation - gas/food for getting to the airport.
Air travel
Ground transportation to pre-cruise hotel in Barcelona
Pre-cruise hotel costs, food, etc. in Barcelona for two days/nights
Ground transportation from hotel to port in Barcelona
Cruise fare
Excursions (include souvenirs and tips for tour guides)
Laundry
Gratuities
Ship specific souvenirs (including photos)
Ground transportation from port to post-cruise hotel
Post-cruise hotel costs, food in Barcelona for one day/night
Ground transportation from hotel to airport
Post-cruise transportation - gas/food for getting from airport home
We don't do Palo, drink of the days, specialty coffee, etc. For souvenirs, we are pin collectors and will probably get a pin set for each of the ports. We will probably get the boys a DCL cruise-specific t-shirt.
What else?