Greece/Turkey with teen and young 20s
 

We're thinking about maybe doing a cruise over Christmas, or the beginning of summer - Greece and Turkey - with sons 17, 20, and 22. All are very interested in history and love to travel, but they are not group activity guys. We want a smaller ship, we don't need/want teen programs but would a mixed clientele as far as age goes, and not too formal. Apart from the Delta Queen (for DH - he worked on it just out of college) and a QE II transatlantic crossing (his 50th birthday present a few years ago), we have not cruised - so we have no idea of the different lines other than Disney (nice, I'm sure, if you have small kids - but it wouldn't at all be for us).

First of all, if you're considering Greece/Turkey, Christmas is probably not the best time weather-wise - May or early June, or early September would likely be better options!
There are many smaller ships that do cruises in that region - we just took a cruise with Louis Cruise Lines on the Cristal - they certainly have all ages (everything from families with young kids, even infants, to retired couples). The ship has about 1000 people, there's enough to do on the boat (small pool, ample sun decks, a disco, casino, etc.). They have some games and activities and such while at sea, certainly nothing that would compare with a larger cruise line, but enough to pass the time I suppose. I thought the ship itself was decent overall.
Downside to the ship - many of the ports, especially Crete and Santorini, there's not nearly enough time to see things. It's a relaxing way to see the Greek islands without having to haul your luggage around and such, just know that you probably won't have as much time as you might like in port. And for ports like Santorini and Mykonos, where the ship can't dock at the actual port so you take little tender boats to shore, make sure you book the optional excurions through the ship so you can get off the boat first! It's also very easy to add on time in Istanbul and Athens before/after the cruise, so you have some more time in those cities. Another suggestion - most ships dock in Kusadasi so you can visit Ephesus (a MUST if you're interested in history/archeology). However, I would HIGHLY recommend hiring a private guide for the day there to take you to Ephesus - otherwise you're in a huge group being rushed through the sites, and there are parts of Ephesus (such as the new terrace houses, which are AMAZING) that you can't get in as part of a large group.
Other downside to the ship - we were NOT impressed with the food. Meat in particular was WAY overcooked (almost to the point of being inedible in many cases). There's enough to eat that's OK, just don't go in with the same expectations you would have on a larger ship! It's not at all formal (they do have a Captain's Dinner one night, where people dress up somewhat, but a nice shirt/slacks for the guys is dressy enough).
So, if you're set on doing a cruise, that might be a decent option. We also did a land tour of Turkey (including Ephesus) on our own with private guides, and personally enjoyed that part of the trip MUCH more than the cruise, but, as I mentioned, it is a relaxing way to travel and get a taste of the Greek islands.

We took our 20 yr-old son on a cruise last May, 10-day round-trip Venice on Holland America's Oosterdam. It went to Athens, Split, Ephesus, two Greek Islands, and we stayed overnight in Istanbul. All three of us had a great time. I second the idea of getting a private guide in Ephesus (and Istanbul).

www.hollandamerica.com

If they are interested in history, they will like this cruise. Do some planning and arrange a guide in advance, esp. in Ephesus,Istanbul and Athens. Cruise line excursions are the ultimate for poor value, lack of control, and frustration. Some places, like the Greek Islands you can do entirely on your own. You won't get to remote villages, but it's your first visit and you're only there a few hours. I've heard that December weather in the Medeterrean can be pretty nasty.

I just wanted to get back to you quickly - I'm now, unfortunately, intent on trip to MD Anderson Hospital in Houston. However, I will return - either once we are there (Monday) and settled or when we get back home. This, and an alternate Namibia trip. have been a very welcome diversion and I appreciate your help! Any other posts/suggestions would be welcome - I'm taking maps with me just to have something to look forward to in the evenings.