I lived in the Orlando area for 15 tears before retiring and am now doing the fulltimer lifestyle (ending my 4th year).
There's an old saying - 'The further North you go in Florida, the more Southern it gets'. Veru true IMHO. The panhandle is definitely Old Florida.
Florida is a really long state so there is a huge winter temp difference between northern and southern Florida. Using the I-75 mile markers, I am about 300 miles from the Georgia state border. Winters up along I-10 are much colder then winters down near Punta Gorda where I am now. And you pay for that. It's cheaper to stay in northern Florida during the winter then in southern Florida. Many people use I-4 as the dividing line.
State Parks are great and do fill up fast.
I would do some internet research this winter (I use RVPARKREVIEWS.COM) in some areas you might like. Read the reviews. Then make some calls in March/Spril of 2018 to make a reservation for the following winter. And make a reservation for the NEXT Winter before you leave that park in the Spring. Maybe make side trips to other places to check them out in case you might want to move.
Keep in mind that many parks give preference depending on your length of stay.
I stayed at Williston Crossings one winter and can highly recommend them. Great place and gets top reviews. Only about 20 miles from Gainesville and not too far to get to the west coast. And I don't agree at all with the tone of one of the previous comments about Williston Crossings. People who stay 4-6 months during the winter tend to view these resorts as their 'home', not as a temporary campground. They come back year after year. I do know some people did tend to make improvements (laid down golf grass sod, etc.) to their individual sites, etc. So what ? It DOES look nice. The RV resort I'm in now uses crushed shell for ther individual sites and some people have used their own funds to replace it with cement ! Who cares ? People must like it here because they have about 500 sites and it's full all winter.
Anyway, I like it in SW Florida. It's WARM all winter. I'm about 3 1/2 hours from the Keys. And the recreatiom opportunities are pretty much boundless. Plus I can wear shorts every day.
I stayed for a week in Christmas RV park on Hwy 50 just east of Orlando and I did like it there too - but all sand. Costly at the daily rate but way better monthly rates. Quiet with good access to the Orlando area in general, and you can get to the Disney parks easily using SR 408 and then 417 (both toll roads). close to I-95 for access to Daytona/Port Canaveral/Cocoa Beach day trips.
My .02