My favorite, mostly due to effective delivery, was at Borghese. Three young ladies were doing a tasting flight and they were novices having fun and asking questions - precisely the kind of audience you want. The guy on staff was engaged with them and doing a great job of keeping it light while still educating and marketing at the same time.
They finished the flight and one asked, timidly, "I'd really like to try the Chardonnay again. Is it against the rules to go back to white after red?" The guy leaned in to them and said quietly, "I could do it, but I'd have to call in the Wine Police to haul you away." Then, after a deliberately timed pause he jovially and loudly added, "I'm kidding! This is wine - you can do whatever you want to enjoy it!"