It takes 8 minutes from where you board a gondola to the top of Sulphur Mountain, the easiest summit in Banff by far. Below you, the Bow River Valley spreads out in a glorious vista of rushing water and jagged mountain peaks below. Your altitude gain from the valley floor to the summit is 698m (2,290 ft.); once you arrive, you're at 2,281m (7,484 ft.) above sea level. The summit offers a new perspective on the peaks you've been straining your neck to gawk upward at; on Sulphur Mountain, you're at their level, so you can look not only straight at them, but also beyond -- to more distant peaks and valleys in almost every direction.
Follow a boardwalk along the mountain ridge as far as neighboring Sanson Peak, where you'll find an historical weather station. Just like anywhere in Banff, even at an alpine summit, there are ways to spend money: a mediocre restaurant, a pricey snack bar, and a gift shop with very typical fare are all willing to lighten your wallet. Don't bother; it's all the same stuff you'll get in town. A coffee in the snack bar is cheap rent for the amazing view, though.