2 dishwashers idea works more in a single person or 2 people household depending on habits. The dishes in the 2 dishwashers are the ones you use frequently, and for occasional times, you get the extras in the cupboards. It's also a decision you make during construction. The difference in cost between a dishwasher and a full bottom row of drawers is not much different, especially if they are beside each other and you already wired up one dishwasher.