A little to fill out salybow's entry:
Griffin Lake State Park features a number of low-key but fun things:
1] Florida's largest known live oak tree - really big!
2] A comfortable-looking campground
3] Nice and easy trails - no hills around here!
4] Canoe rentals, very reasonably priced. Depending on your skills, energy, etc., you can spend a lot of time and wend your way well out into the lake.
I'll also put in a word for Homosassa Springs! Great fun, there.
Welcome to your guests. May they enjoy enough to decide to come permanently!
SWR