Traveling to Florida with Kids

We are planning a family trip to Florida later this year, and I need some suggestions! We would prefer to be in the Florida panhandle (closer/less travel time). We have 3 children, 5 years old and under. Does anyone have any suggestions as to the best beach to go to, where to stay, activities for kids, etc? I want somewhere less crowded. I would love for there to be lots of shells for my kids to look for, and I want somewhere that also has some kid friendly activities outside of the beach. I was thinking late September for timing. I don’t want it to be super hot on the beach, but I would like for the water to be warm. Any suggestions/tips would be greatly appreciated!