The Costa Concordia, on the other hand, is precisely like that. It is — or was — a modern mega-ship, launched in 2006, carrying 4,000 passengers and crew. It’s owned by Carnival Corp., the largest cruise line company in the world. There will be major and lasting repercussions to the fact that it has run aground and rolled onto its side off the coast of Italy, killing at least three people. (At this point, the BBC reports that dozens more are missing.)

One consequence will be a lasting and disturbing impression on the public which, despite occasional reports of fires and passengers going overboard, had grown accustomed to the idea that modern mega-ships do not sink. The other will be increased scrutiny in the United States and Europe of an industry that operates largely outside the regulatory bounds of both.

Carnival — which owns Carnival Cruise Lines, Holland America, Princess, Seabourn, P&O, Cunard, Costa, AIDA and Iberocruceros — will have a lot of explaining to do. But I suspect the other major cruise lines are worried, too.

That’s $72.50 per person, per day, well below my bargain threshold of  $100. People living in the Northeast can skip the airfare, which makes the deal even sweeter.

This fare is available on the Norwegian Gem on Nov. 13, 20 and 27 and the Norwegian Jewel on Nov. 7, 14 and 21. The ships leave New York, spend a day at sea and then stop at Port Canaveral, Fla.; Great Stirrup Cay, Bahamas; and Nassau, Bahamas, before spending two days at sea on the return to New York.

Ocean view cabins are available at $715 per person and balcony cabins from $755 per person.

So far, the offer is good only on Royal Caribbean’s  European itineraries. Passengers must still vacate their cabins by 9 a.m. on the final day of the cruise. But for the additional $35 per adult ($17.50 per child), passengers may enjoy the pools and some other amenities until 90 minutes before the ship’s next departure.

Traditionally, passengers must vacate cabins and wait in crowded common areas of a cruise ship to be called in groups to collect their luggage and leave.This is the ugly process that my husband and I call “get off my sheep,” in honor of the way Royal Caribbean’s Norwegian captains pronounce the word “ship.” (Not that the captains ever say it quite so tactlessly.)

Passengers who might otherwise have to cool their heels at an airport waiting for an evening flight, or take a post-cruise excursion to pass the time, can now stay on board and splash around. One wonders what the overworked staff, who get only a few hectic hours a week to work without passengers in the way, must think of this. I’m sure they’d be too polite to say.

The Celebrity Summit is repositioning from the Northeast, where it has been doing Canada and Bermuda cruises, to the Caribbean on Oct. 24. The ship will sail from  Bayonne, New Jersey,  proceed to Bermuda for an overnight stay and then sail to St. Thomas and  Puerto Rico.

Inside cabins are listed at $399 a person, which comes out to $514 with taxes and fees. That’s a terrific itinerary at $85 a day for a cruise line that’s on the upscale side of the mass-market lines.

Of course, you’d have to buy transportation back from Puerto Rico.  JetBlue has one-way fares in the $200 range to JFK and LaGuardia. Unfortunately, fares to Bradley are substantially higher right now.

The move comes after Park West lost a $500,000 judgment in a countersuit filed by one of its most vehement critics, according to the Detroit Free Press.

This is a good move on Royal Caribbean’s part. Let’s hope the other cruise lines follow suit and that they don’t replace the art auctions with something equally obnoxious.

And if you’re going on a cruise, remember my simple advice: avoid the art auctions, the jewelry, the casino and the spa treatments. In every case, you’ll get a better value on shore.

Questioned about passenger spending on the cruise line’s new mega-giganta-ship, Oasis of the Seas, Goldstein said the ship “has proven to be an even stronger onboard revenue generator than we had foreseen.” Passengers are not only paying premium rates to sail on this massive ship, they are spending quite merrily on extras when aboard.

Royal Caribbean has given them no shortage of opportunities to do this, as Sloan points out, with “an industry leading number of extra-charge restaurants, bars, stores and other outlets where passengers can spend money.”

Despite this trend toward expensive add-ons and “unbundling” of previously all-inclusive amenities, I still believe a cruise vacation can be an excellent value. The key is to find a good rate and enjoy the experience of being at sea while resisting the temptation to shop and spend just for the sake of shopping and spending.

My own strategy is never to book the newest ships, which rarely offer a good value, but to wait and sail on them a few years later, when the buzz has faded, some new mega-ship has stolen their cachet and the rates have dropped. If the ship was so much fun when it was new, it still ought to be plenty of fun three or four years later.

When on board, I enjoy the all-inclusive food and entertainment but resist the expensive shore excursions, overpriced spa treatments and questionable art auctions. I can usually arrange my own shore activities for less than the cruise line charges, and I can certainly get a less expensive massage or a better deal on merchandise in port than on board the ship. 

My goal, in short, is to avoid being an onboard revenue generator —  though I hear there’s one of those born every minute.

Travelocity is offering this rate on sailings that depart Miami on Nov. 29 and Dec. 5, 2010. Cruise.com has the same rate on those dates and also on Dec. 13.

The cruise goes to Key West and Cozumel, then spends a day at sea before returning to Miami. I’m not crazy about the port schedule — the ship docks in Key West only from 7:30 a.m. to 2 p.m. and in Cozumel from 1 p.m. to 10 p.m. Also, keep in mind that the Imagination is one of Carnival’s older ships and that the cabins at this rock-bottom price feature upper and lower bunks — not romantic.

Nevertheless, it is an excellent deal, and cabins with beds that combine into a queen are available at $10 or $20 more per person.

These rates include, of course, all meals and most entertainment. If you avoid the high-priced shore excursions and the on-board art auctions, you really don’t need to spend much more beyond the tips, which usually total about $9 a day per person.

The Carnival Liberty leaves Miami on Saturday, Dec. 4, 2010 and stops in Cozumel, Grand Cayman and Ocho Rios before the return to Miami.

For a few bucks more, you can book the Carnival Valor, which leaves Miami on Sunday, Dec. 5, 2010 and stops in Grand Cayman, Roatan, Belize and Cozumel before returning to Miami. The cost is $447 per person, taxes and fees included, for an inside cabin, double occupancy.

These are Carnival’s “early saver” rates, which require a non-refundable deposit at booking. An additional warning: Carnival “reserves the right to re-instate the fuel supplement for all guests at up to $9 per person per day if the NYMEX oil price exceeds $70 per barrel.” That means after you’ve paid, folks.

It’s a very nice price for a Bermuda cruise, which tend to be comparatively expensive. For those of us who live in the Northeast, it’s an opportunity to cruise without paying airfare.

The week-long cruise starts with two full days at sea. The ship spends three nights at King’s Wharf, Bermuda, and then a day at sea on return to New York.

Only the April 25 voyage is available at the $399 rate. Summer rates for the same route top off at more than $1,000 per person.

This rate is available directly from Norwegian and from several cruise agencies.

Cabins with balconies start at $699 on the same sailing, which comes to $889, total, per person.