Two outlines
Plan half a day
A full day on that ridge is more sitting than most families want. Half a day is honest. Here are two outlines I give when someone corners me next to their rental car. Times are walking times plus waiting, not a promise.
Morning, with kids
Park earlier than you think. Eat in town; the summit restaurant is expensive and slow when it is busy. Take the first slot you can live with. Ride up. Walk as far as the first long stair flight. If someone is done, you are done. Ride down before the lunch crush hits the base. Keep a layer in the pack even in July.
Evening couple
The evening run puts you on the ridge when the valley shadow is already climbing. It is prettier. It is colder. Night on the ridge is not a dinner date unless you already accepted the prices upstairs. Walk the boardwalk while you still have light. Do not start the last stairs at dusk in October. Come down on the cabin; walking the trail in the dark is a different job.
Neither outline includes shopping in town, a hot spring, or a second mountain. Stacking those on the same morning is how people end up angry in a line. Pick the ridge or pick the rest of Banff. The gondola does not owe you both.
Drive time from the park gates into Banff is its own gamble on long weekends. I start the clock when I leave the motel, not when I see the lift.