Ouch! Sorry to hear about the van and the dog. Something about going on vacation sure does seem to drive big, unplanned expenses. My dog had dental surgery for $550 three weeks ago, but that sounds cheap now!
As for Cozumel beaches, Paradise Beach seems to be the one that comes up most often with good reviews. Several commented on the awesome guac! Most said the cab ride was $14 each way. The other one that gets a lot of "positive press" is Nachi Cocom. Great service, but I think you have to pay. I found a great beach map here:
http://cozumelmexico.net/Cozumel-Beaches.html.
We signed up for the Cozumel ruins and beach tour which starts at 12:15. The complaint some had for that is that you only had an hour at Playa Mia. So, I thought we would hop off the boat first thing in the morning and take a taxi to Paradise Beach and stay there for as long as we could, then taxi back to the ship to catch our excursion. If we don't get up early enough that day (likely....

), we will just explore near the ship and shop until excursion time. The beach trip in the morning may be rushed, but we sure would like to have more time to try out the inflatables and enjoy the beach.
We just booked our Grand Cayman island tour and stingray city snorkel through Native Way online. Here is what they sent back as a reservation confirmation:
"Pleasant Greetings from Grand Cayman...and thanks for contacting us!
I have reserved 4 spaces for you on our December 15, "Stingray & Island Tour" excursion. The reservation # is xxx. The price is $60 USD per person. We no longer require that you provide your credit card number to guarantee your arrival, so you are all set! You will pay on our tour boat. We accept cash, Traveler's Checks, MasterCard, Visa, American Express and Discover. If you pay via credit card, you will be charged a 4% processing fee.
The tour departs the pier at 10 AM Eastern Time and completes at around 2 PM Eastern Time. We ask that you check in no later than 9:45 AM Eastern Time. When you come ashore, look for the person carrying the sign that says Native Way Watersports. You may also ask for us at the information booth at the cruise ship terminal.
You will be driven by bus to popular locations on the island. You will also be taken to Stingray Sandbar by boat. On the boat, we provide free use of all snorkeling gear and vests, food for the Rays, and complimentary punch and bottled water. After the tour, you will be driven back to the cruise ship pier.
We ask that you provide at least one week advance notice to cancel. If your ship is unable to dock in Grand Cayman, we will automatically cancel your reservation, at no cost to you.
Let me know if you have any other questions.
I look forward to seeing you in Grand Cayman on December 15!
Sharon Ebanks"
Sounds convenient and professional. I am guessing the complimentary punch will not be spiked.

Good info on the credit card; we will be sure to bring cash. It doesn't say that they will drop you on the beach, but I
think I read that they will.
Hope this is useful rather than time-wasting! If I should quit rambling on, let me know!
My kids are bugging me every day about when we get to go. Guess I'll need to make one of bevtoy's cruise chains!