Never lead with the vacation. Lead with the value of the purchase. Introduce the incentive only after the buyer has emotionally committed to the product.
Use it to break a stall: 'We can't hold this price beyond today, but we can include the getaway if we sign by close of business.' That single line moves 22% of stalled deals to close on the same day in field tests.
Use it to reduce remorse: hand the certificate at delivery, not at signing. Customers remember the moment forever.