The Un-Spangled Banner? The Eiffel Platform? Strange landmarks star in a campaign to promote Travelex foreign-exchange services. The $4.3 million campaign, from M&C Saatchi, London, features shots of incomplete icons-such as Big Ben without a clock or a dollar bill without a president's picture-and the tagline, "You'd notice if we weren't there." Ads appear in in-flight and financial magazines. Travelex's parent, TravellersExchange Corp. recently bought Thomas Cook Global & Financial Services and the rights to market Thomas Cook Travellers Cheques. Art director: Ali Peaty. Copywriter: Nicky Bullard.