Just got back from a week in Sanibel. This was a family vacation, so I had limited time on the water. If you want to do-it-yourself without a guide, stop in (or call) the Bait Box shop on Sanibel Island. Very friendly people that will set you up with maps of the island and show you where you can go on your own - they do give good advise.
There is a great flat on the South shore of the Sanibel toll booth. This flat is wind sheltered from North wind, and also is next to the deeper channels --- so you can wade out to the edge of the flat and cast into the deeper tough/channel for trout & ladyfish, etc., or wade the shallower grass flat portion for redfish. Late February on this flat should be nice for incoming reds and snook.
I also rented a motorized canoe in Tarpon Bay (part of the Ding Darling reserve). There were oyster bar islands in the middle of the bay that I caught dozens of 18-24 inch specs of a charteuse/ white clouser. The bay has great mangoves, and in a month or two, I can see the place filled with redfish and snook (the 65 degree temps when I was there was just a little too chilly).
I took a 6wt for the trout and ladyfish, and had my 8wt in case I started to see large redfish or snook (but didn't). Floating line was the stable, but there are some places there to blind cast the channels if you want (sinking/intermediate). If fishing the flats, make sure you have assorted flies to handle the flats grass and other interference.
Best of luck and tight lines,