We've done both. Loved both. I wish they would combine and do a DD Eastern!!!
I loved the DD because of the 2 stops of course. Pure heaven!!! Costa Maya was nice enough, we really enjoyed the wave runners. It rained which was ok. The people in port were extremely pushy, more so than any other port including Nassau.
Of course Coz. was still recovering and we had to tender and our day was way shorter than expected, but we had a great day snorkeling with Eagle Ray.
We LOVE the Eastern. The first 2 days at sea are awesome. It gives you a lot of time to settle in, RELAX!!!!!
We loved both the ports as well. St. Martin we spent the morning at the beautiful Dawn Beach. Then we came back to get cleaned up, eat and shop. There is a very nice beach-Great Bay Beach right at the port. The taxis and water taxi is very convenient and easy.
St. Thomas we did the best excursion out of all of our trips with Capt. Nautica. Highly recommended if anyone wants a great snorkeling experience. We didn't shop much, just at the dock.
I would love to do another Eastern, but unfortunately, it doesn't sound like it will sailing in the summer of 2008.