Not to be a thread blender, but Cyrkle isn't a bad example of sunshine pop.
Both Dawes and Danneman became professional jingle writers after The Cyrkle disbanded. Dawes later wrote the famous "plop plop fizz fizz" jingle for Alka-Seltzer. Danneman wrote jingles for Continental Airlines and Swanson Foods. He penned the original 7Up Uncola song. In 1977, Dawes produced Foghat. [source: Wikipedia]