I'd support the SE coast as a great spot in December - park yourself somewhere in Broward county, where you could easily get to Dade and Palm Beach counties, and you'll have a myriad of places within 1 hours' drive. Everglades National Park, Key Biscayne, Matheson, Lucky Hammock, Loxahatchee, AD Barnes, Brian Piccolo Park, Wakodahatchee Wetlands, Green Cay Wetlands, Arthur Marshall Wildlife Refuge, Okeeheelee Park, Grassy Waters, Wellington Wetlands, various coastal and beach parks and spots, and even good spotting at small local community parks and oddball spots like cemeteries. Willing to drive 2 hours, and you can open up some spots in the Keys, and up to Viera Wetlands and Merritt Island, as well as Lake Okeechobee.
There are almost too many places to access around here, and winter migration should be quite strong that time of year, as well as a lot of the big waders nesting.