We are taking the Grandeur of the Seas on March 1 from New Orleans. Its during Mardi Gras and we wanted to experience it. Going there a day early. If you do that, the Hotel Monaco is about the only place you can stay for one night. During mardi gras its a 3-4 night mini stay at the hotels. RC is in "cahoots" with Hotel Monaco. It goes to Progreso and Cozumel Mexico and Key West overnight (noonish-7a.m.) with days at sea. this is not in the RC booklet, but you can find it online. Either month is fine. Less likely to hit a snowstorm I guess in March. We are from WI and hoping we don't have any delays.
I have sailed on the Explorer twice both times in March but both times we have sailed the Eastern Caribbean. We are sailing her again this coming March to the Western Caribbean. The water was a bit cold yet it was fine once you got in, which might not be true for Feburary. I would recommend March, but NOT the end of March when you have alot of people on spring break. We did this the first time we sailed EOS and there were approx 3200 plus passengers were aboard. Trying to get an elevator was alot of fun. We learned to go ahead and get on as eventually the elevator will be going in the direction you want to go. You're going to love this ship. Be sure to catch the ice show.