For many of the aforementioned reasons, we will generally seek to arrive day - or even two days - prior to cruise departure. That gives us a wider selection of flights, less crowded conditions, and we can deal with jet lags, delays (aircraft, baggage if appropriate, etc.) much more easily.

We've also seen a number of people who have not made the cruise because of delays - some of them arrived a day or two later, some arrived on time but we departed without their having baggage, etc.

December 2012 we did arrive the day of cruise departure - we flew SMF-LAX-JFK-SXM - and it was slightly nerve wracking given weather, possible mechanical problems (AA 767-223ERs are being replaced with A321s on LAX-JFK routes, and the 762s are aging badly with lots of mechanical issues). Delays or cancellations would have resulted in no further travel that day due to full lights to SXM. We made it with a few hours to spare, but I'd prefer to not do this in the future - and the farther the cruise begins, the less we will do this (our next cruises originate in BCN, KEF and ATH - we're arriving a couple of days early, particularly since some cruise companies have been offering two days pre- or post-cruise lodging as incentives).

(This relates to experience with perhaps 40 cruises / liveaboard dive trips).