Thank you for the suggestions.
I assume inventory is different for RCI points and RCI weeks. If I am depositing my Wyndham points which RCI system is this searching?
Yes there is more inventory in RCI points than there is in RCI weeks which is what a Wyndham deposit has access to. But there is still a lot of availability and there are always new stays being added to what is available. I would think if anything came open at those resorts that you would be able to book them through a deposit into RCI. I would suggest you set up a search if you like any of those resorts.
I would never depend on a search or deposit getting you a Christmas or Thanksgiving week at a Southern Florida resort. Not saying it could never happen just that there is such a big demand making it pretty difficult. After you've checked out the different areas, visited the resorts and find the ones you like the most I would suggest buying the holiday weeks you want.
If you aren't familiar with the area you may not know that you have to pay a toll to use the bridge/causeway to get to Sanibel and Captiva. But you don't pay to leave. Some people fuss about the toll and refuse to stay on Sanibel or Captiva because of it but we and many other people consider it worth it because we love Sanibel and Captiva for the beautiful beaches and shelling. I think the toll is $6 per car. Sorry we have a SunPass transponder so just drive through. If you will be driving or even renting a car in Florida I suggest you buy a SunPass transponder $20 which can be transferred from vehicle to vehicle or a sticker $5 which you cannot transfer. Many Florida roads are cashless now and you will be billed by plate. Using the transponder or sticker gets you a discount on the tolls too. You can buy either on the SunPass website or look at the list of places you can get them once you get here.
You also learn to buy groceries before you get to the island so you don't have to pay the higher prices of the stores on the island for everything you will need just the stuff you need more of. There is a very nice Farmers Market on Sunday mornings on Sanibel. We live in the Fort Lauderdale area and take I-75, Alligator Alley, across when we go to the resorts on the West coast. We bring some stuff with us but usually have lunch in Naples then do our shopping at the Trader Joe's and Whole Foods there in Naples before heading to the island.
If you are staying at a resort on the Southwest coast of Florida and flying you may want to check flights into Fort Lauderdale. It would be about about 90 minutes to Naples, probably 2 hours and 15 minutes to Sanibel but possibly a few minutes longer depending on where on Sanibel you're staying and probably 2 hours and 50 minutes to Captiva. The local airports for that area are in Fort Myers and Punta Gorda. When we still lived up North we've also flown into Tampa and driven to Sanibel which was probably 3.5 hours. You could also fly into Orlando spend a night or two there first and that drive is close to 3 hours to Sanibel.
Have you thought about Sarasota. There are a lot of nice resorts in that area too. Sarasota is where the temperate zone changes to sub-tropical. If I wanted to have a better guarantee of warmer weather for a family vacation over Christmas I would probably look at heading south to Sanibel, Captiva, Naples or even Marco Island. MI has a lot of lovely resorts you can book through RCI.