I'm going on a cruise in a couple weeks and I was wondering if anyone had any suggestions for excursions to go on. Me and a group of older (and relatively sober) college students will be on the Norwegian Spirit travelling to Cozumel, Costa Maya, Belize City, and Roatan. Also, what are the benefits to booking ahead of time versus on the cruise itself? Any other tips or suggestions would be greatly appreciated. Thanks for your help!