Cruise Excursions??? What's your experience?

I travel quite a bit, and whether I do a formal shore excursion really depends on where we are and what is available. I find it helpful and very interesting to do a lot of reading before each trip! In the Caribbean I generally skip formal excursions and go off on my own in town for some shopping, sightseeing on foot, and local cuisine. However, I have swum with dolphins in Acapulco, spent a day at the Vatican, gone to Corinth and Mycenae (Greece), and did an overnight in Cairo, which included the museum, evening sound and light show, and sunrise at the pyramids -- all excursions arranged by the cruise companies, and all wonderful! All of the excursions I have taken have been through the cruise company, and several times they have run late and they have held the ship for us so we were not stranded anywhere!

A few of them are lifetime memories and worth every dime:

1. Stingray City in Grand Cayman.
2. Cave tubing in Belize.
3. Chichen Itza in Cancun.
4. Dunns River Falls in Jamaica.
5. Swimming with sea turtles in Barbados.

The rest are OK. It just depends on where you are going.

It depends on what you want to do while you are in port. If you just want to get off the ship, wander around and go shopping, I would say no because you can do that on your own for free. If you want to do something more adventuresome, it may be well worth the cost of booking a shore excursion through the ship because the cruise ship company picks reliable vendors that have a good safety record and if for some unforseen reason you are late getting back to the ship, the ship will wait for you. As another answerer mentioned, for some shore excursions the only way to do them is through the ship because the cruise lines have all of the spots booked. If you want a less adventuresome shore excursion and are willing to do your own research to find an availab, reliable tour guide, you may be able to find doing the same shore excursion for less, but if you are late back to the ship it will leave without you. Here is an article about a cruise with a mix of shore excursions - some booked through the ship and some not: http://www.squidoo.com/Mexico_Cruise

They do tend to be overpriced, and many of them involve a whole motorcoach (or several!) of people.
HOWEVER, that being said, if you are not a confident traveler, it may be to your benefit to do your sightseeing in that fashion, since someone else has done all the legwork to research and arrange things.
I'm at the point where the only time I will buy an excursion from the cruise line is if it takes me more than an hour or so from where the ship is docked, or if the activity in question cannot be booked except through the ship (some tourism operators sell all their slots to the cruise lines when there's a ship in port).

It really depends. When we stopped in St. Thomas, we did a once in a lifetime dolphin encounter! It was pretty expensive, but it was so cool! In St. Maarten, our snorkeling excursion got cancelled, so we decided to go to the airport when the runaway is about 100 feet away from the beach, and that was very fun! When we go again, I don't want to go on any excursions unless they are once in a lifetime, like the dolphin encounter. We have more fun making our own!