First up is the classic Diet Pepsi commercial from 1967. The tune playing in the background is "Music to Watch Girls By." It was turned into a hit instrumental by The Bob Crewe Generation, going to #15 on the Billboard Hot 100. A version with lyrics was later performed by Andy Williams, going to #34 on the Billboard Hot 100 also in 1967.
Second up is possibly the most famous Coca-Cola commercial of all time. The "Hilltop" ad was first aired in 1971. The song featured in the advert, "I'd Like to Teach the World to Sing," was later expanded (with all references to Coke dropped) and became a hit record for The New Seekers. It went to #7 on the Billboard charts.