Sorry to hear about your grandfather. Hope he is doing better.
Discovery Cove is neat. I liked it more than my wife did. If you have never swum with dolphins, you will love it - for my money, it was the second best experience of the kind I have had (the best was in the Bahamas).
The best part of the Cove (for me) was the snorkeling. The fish there are well fed and cared for (I know there are people who will disagree with me, because the fish are contained, but they come across as well cared for), and as a result are huge compared to what you will see out on a reef (I am not a diver, so can't say what you'd see in deeper water, but compared to what you typically see from the beaches, they are whoppers!). There are tons of rays and lots of fish. The baracuda there are the scariest things I have ever seen in the water (they are behind glass, which is not immediately evident, but yes, this is a controlled enviornment).
If you have never been to Grand Caymen and done Stingray City (and even if you have), the stingray pool is pretty neat. Lots of kids, though. If you are patient and relaxed, its easy to see patterns of how the rays move around, and then get to a place where they will swim right by you, so you can pet them as they go by. Just know that they are intimately familiar with people, and are not thrilled with how people chase and try to grab them - so they are pretty wary (moreso than you find in the wild).
One nice thing about Discovery Cove is that pretty much everyhting is included. The food is quite good, and the lines when we went were not bad at all. One thing to keep in mind is that they take a picture of your group, which is included. If you like the picture at all, and want to frame it in a Discovery Cove frame, get it there. When we went, we thought we'd just get it the next day at Sea World, or online, but no dice, and it is the one minor regret we had about the viait - so be forewarned.
Overall, you will have fun. It is pretty tightly controlled, which grates at me, but it is a good thing, since most people seem to do some pretty stupid things, and the fish need to be protected.
I know you read the last blog I did (thanks for the kind words), and if you go to
http://www.timethiefsports.com/Cruise3/18-Dec.html you'll find some pictures from the visit. Not sure if they will help, but it couldn't hurt. Feel free to PM me if you have a specific question or three (I usually have three or more, myself).
Have a great trip!
Keep Smiling!!!