Marco Island is a great place to be in January. You can target redfish and speckled trout on the flats and snook and tarpon in the backcountry. You can actually drive out a few miles on Tamiami Trail (US 41) and park anywhere on the side of the road and fish the canals from right next to your car.
As far as guides are concerned, there are two I recommend Bill Blanton and Charlie Wright. Bill Blanton is well known in fly fishing circles and is usually heavily booked.
http://www.flyfishtheglades.com/index.html
Charlie Wright specializes in kayak fishing, which is cheaper and more flexible. Kayaks are particularly suited for fishing in that area due to all the protected, shallow flats. You will probably need to practice casting from a sitting position if you go this route. It’s not hard and you rarely need over 60 foot casts.
http://www.evergladeskayakfishing.com/ten-thousand-islands.htm
Two web sites you might check out are
http://paddle-fishing-forum.com/index.php
which is primarily a Florida Gulf coast kayak fishing site and Florida Sportsman
http://outdoorsbest.zeroforum.com/zeromain?id=1
which is a more general fishing site for the state of Florida.
As far as equipment, I would recommend a 6wt and an 8wt.