You should definitely take your kids to
Goofy Golf in Ft. Walton Beach (401 Eglin Parkway NE, Ft. Walton Beach). It's a Ft. Walton Beach institution that has been open since 1958, and I've been playing putt putt there since I was old enough to walk. The prices are super cheap ($3 for adults and $1.50 for kids per round), and it is a really fun course for the whole family with far more interesting obstacles than more modern putt putt courses that cost way more.
You could also take your kids over to
The Track in Destin if you want to do some different recreational activities besides the beach. They have go-karts, bumper boats, arcades, bungee jumping, etc. It is right across the street from the Back Porch, where you could hang out at the beach and grab some drinks afterwards.