Hi Honeybound!
I take it you plan on leaving your husband behind on some excursions?

I have spotted many lone female travelers while doing organized excursions. You really blend in and folks cannot tell if you are alone or not. If you venture out on your own, stay on the beaten path (shopping street, places where there are larger number of folks). You might get approached or cat-called but if you have the New Yorker approach, that won't bother you. Simply ignore them. Never slow your pace to even allow for an encounter. Being a former police officer, I am sure you have encountered much worse. LOL. Your ports of call are pretty safe areas.
The case in Aruba is, sadly, a young girl-- perhaps somewhat naive or distracted by the island paradise-- who was probably seduced by the "charming" boys and either they slipped her a date rape drug, she said no and things got violent or it got out of hand somehow. One does not know how alcohol played into this horrible situation. These situations are extremely rare but young girls are hit on all the time...not only in island countries but all over the world. One must keep their wits about themselves.
Sometimes, I have seen lone female travelers get befriended by mature couples and they take a tour or shop together. Sometimes the woman enjoys a shopping partner that is more enthused than her husband.

The husband also appears to be relieved of his duty. (I am not trying to play on stereotypes but I only know a few husbands that might scream "Hot diggity, we are going to the souvenir shops!" LOL). Anyway, keep an eye out for such couples, because being a tour or shopping pal is beneficial to all.
If you enjoy ruins, Tulum is quite picturesque and overlooks the ocean. The cliff to a small beach is dramatic and beautiful. The ruins are not as large as Chichen Itza but they are much closer and easier to get to. Part of Against All Odds was filmed there. When you look at the main pyramid and look to the left, there is a little cave. Beware of spelunking in there because a lot of bats live there (or at least they did when I was there.)
Here are some photos of Tulum:
http://www.differentworld.com/mexico/places/tulum/tulum.htm
Royal Caribbean probably offers a Tulum Express tour, which drops you off in San Miguel in Cozumel. You will probably have an hour to walk around before talking a taxi back to the ship.
I hope this helps.
