Mayan ruins excursion in Belize was okay, but 4 hours of it is bus ride...... so that made it barely worth the cost.
Unless you want to buy a bunch of stuff, I would advise skipping the tourist shops on Cozumel. Pushy, aggressive merchandise hawkers got on my nerves immediately. I only went along to carry my wife's packages as she shopped for gifts. Although a highlight was lunch at the Thirsty Cougar!! That was an amazing table of food; $50 for 4 people, including drinks. Unless you are a very heavy eater, share a meal, because the pile of Fajitas Nachos I got was HUGE! My wife got some onion rings and we shared both dishes. We couldn't even finish them.