Wouldn't it be nice if you could make a reservation at a buffet? All you'd have to do would be walk up to the cashier, state your name, and be shown to a table, in the usual fashion.
Well, you actually can make reservations at two Las Vegas buffets.
The first is the Bacchanal Buffet at Caesar's Palace. Reservations aren't mandatory, but you can reserve via OpenTable or by calling them directly.
The second is The Buffet at the Wynn Las Vegas. You can make a reservation on OpenTable or on The Wynn's website.