Lucky you, I wish I was heading back to the Cayman Islands! Just wanted to share some GCM advice from our recent trip to GC and LC.
If you have a long layover at GCM airport, you don't have to spend the entire time hanging around the airport; the George Town Yacht Club is about 3 minutes away and they provide a free shuttle service:
George Town Yacht Club
https://tinyurl.com/yf3wgx29
On weekdays they open at 11 am but they are open for breakfast at 8:30 am on weekends.
After you arrive at GCM and go through immigration, get your bags and go through customs - then head over to the Cayman Airways ticketing counter to check in for your flight to LC and check your bags.
If you are bringing any duty-free products with you like alcohol, put it carefully secured inside your checked luggage before rechecking because you cannot take more than 3 oz. of liquid or gel through security. Each adult can bring up to 1 liter of liquor with them into Cayman duty-free. You can usually pick some up at the duty-free shop in the airport at your last stop before leaving the US.
After you are checked in with Cayman Airways, grab your carry-ons and go outside the door of the Ticketing Hall. You will see a placard/sign advertising the GTYC and listing their phone number. I think that the van makes periodic rounds but we always just call them and they show up quickly.
Tell the van driver what time you want to head back to the airport and she/he will be waiting to take you back on schedule. You will have to go through Security at the airport to access the Departure Lounge to catch your flight to LC. The GCM airport has added more Security lanes and it usually goes pretty quickly but don't cut it too closely, especially since many of you are traveling on the weekend during the high season.
When you get to the GTYC they will stash your carry-ons for you. You can eat indoors or outside and there is a lovely view of the harbor. We like their cracked conch but their menu is pretty good - much better than the airport venues! They are owned by the same people that own Macabuca and the Cracked Conch.
Another comment, I spent lot of time in the GCM airport in November because we had some weather-related delays and I was freezing cold! I don't know if it was a fluke or if it is always that cold, but you might want to wear/carry some light-weight long pants and a light long-sleeve jacket or shirt.
We were wearing shorts and tees because we had just spent a week on Grand Cayman but luckily I had a pair of yogo pants in my carry-on, but I finally had to give in and I paid too much money at the airport shop to buy a light-weight jacket that proclaims "Cayman Islands" from every possible angle.
So if you tend to feel the cold you might want to be prepared. And it's not a bad idea to have some long pants, a light jacket, socks and shoes with you, anyway. If the wind drops you can become a mosquito target on LC, especially at dusk and at night.
Have a great trip and I hope that you have good weather and diving!