Click a bathroom sink to fit it with a paper towel dispenser ($30) or a hand dryer ($90).
The dispenser holds 20 towels. Each guest takes one, and the busboy refills it from the pantry like the toilet paper and soap. A guest who finds it empty is unhappier.
The hand dryer never runs out, but guests spend two extra seconds drying their hands under it.
The starting bathroom comes with a paper towel dispenser.
The screenshot shows the dispenser (left, with its towel and soap bars) and the hand dryer (right) with a guest drying their hands.