Booking 11 days in advance pays off well when choosing Costa. We found a $329 fare online and were told we were guaranteed a room. We ended up with a nice balcony room portside.
A brief review: The ship was very nice. The staff were excellent. The fitness center had old outdated equipment. The entertainment was better than on NCL. However, there were no ushers in the theater on any evening. Food was below average. The quality food on the ship was the pasta and pizza..... so it's not recommended when you are trying to lose weight. I gained 7 pounds, and I usually lose weight on ships. Decent salads were lacking.
The ports were fine. One recommendation is in regard to St. Thomas. Rather than paying the $20 to take the gondola up the hill, just take the short switchback road and walk. It's a nice walk and your drink at the top will feel more refreshing. A big warning is to avoid a company called "Island Marketing Highlights Tour", who also use the site: "stthomascruiseexcursions.com". I booked a tour with them and they did not bother to show up. When I phoned them they did not seem to care. A lesson was learned.