The goal of the first trip is that they want to go again. Everything else is optional, including the hike.

The first trip sets whether camping becomes a family thing or a thing the kids endure. Almost every family that gets this wrong got too ambitious: too far, too cold, too long, too scheduled. Aim absurdly low and you get a second trip, which is the only success metric that matters.
A backyard night costs nothing and surfaces every problem while the house is ten steps away. If the yard night goes badly, you have learned something cheap.
Close enough to bail without it being a disaster. Knowing you can leave takes the pressure off, and that changes how the whole trip feels.
Kids get cold much faster than adults and a cold night is the fastest way to a child who refuses to go again. Rate for well below the forecast, add a warm base layer, a hat, and an insulated pad, which matters more than the bag.
Their own light is the single most popular item on any family trip. Then give them a real task: gathering kindling, setting out plates, pumping water. Being useful is what makes them feel like they belong there.
A campground is not the place to introduce new food. One familiar dinner and something warm and sweet at night buys enormous goodwill.
One short walk, and the rest unstructured time near camp. Small kids are usually happiest with a creek, sticks and dirt. The scenic hike is for you, not for them, and it can wait a few years.
Yard first, close site, overdress the sleep system, headlamps and real jobs, familiar food, and a quarter of the plan you had in mind.