Yikes, I think my last 7 day cruise the bill at the end for the two of us was about $450 (and we had about $200 in onboard credit, so the final bill was about $250).

Figure that includes tips, plus 2-3 drinks a day for each of us. Plus on that cruise my wife did the Chef's table dining, which was $75 in and of itself. Other than that, we don't generally do any of the specialty restaurants. (Obviously a heavier drinker would spend more of course.)

No cruise line excursions on that one, think we spent $150 for a snorkeling trip in St Thomas, and about $80 for golf cart rental in Grand Turk, that'd be in addition to the above.

Personally, I think the largest onboard bill I've had was the 2 week Amazon to FLL cruise, that ended up being just over $2k I think (plus we had a $300 independent excursion in Manaus). Course, part of the reason that one was so expensive is because it included a $950 piece of art and $200 or so for the navigational chart, so it was significantly higher than our usual bill.