We are staying for four nights for the first time in September. I know we want to ride bikes and kayak. We are park hopping one day.....but what should we do with the rest of our time. What does a typical day there look like for most of you seasoned

Fort Wilderness people, lol? It will just be the husband and I....no kids. Looking for ideas.......
Well, to be honest, there is no 'typical' day there. It is as different and varied as the people that camp there.
By the way, unless changed, don't remember seeing kayaks there, only canoes.
Someone can correct me if they've been added.
Some people stay there and never go to a park, some eat all their meals there, many ride bicycles, use carts to loop. There are boats to rent, to fish, play around on in the lake, horse riding, camp fire shows, etc, etc. So, a 'typical' day there is what 'you' make it!!
For us personally, we love the ambiance, but spend most of our days in the parks, or going to downtown Disney, or enjoying some of the other resorts.
We usually hear (not always see) the electric water parade and fireworks. We don't personally watch the fireworks from the beach, as so many are obstructed by the Discovery Island trees, but many do enjoy it.
It is a place to enjoy the outdoors to your hearts content. You can explore for yourselves when you arrive. You 'will not' be disappointed whatever activities you decide to avail yourselves of. Have a great trip!!
