If you can tear yourself away for a solid day trip (about 7am to almost 10pm) then Chichen Itza is for you!
If you were not going alone I would say to be sure to go downtown (not the Hotel Zone) and have a meal and few drinks down there. Something we have not done and will be sure to next time is the Fri night booze cruise....I hear its a blast.
Definitely the friday nite booze cruise. Sergio does a great job making sure everyone has a blast. They also say the adult only day cruise to Isla Majures is also worth it. We've never done it,but don't think I've ever heard anyone who was disappointed. I think that one goes on Tuesdays.
