Fitz and the Tantrums; Metric; Porter Robinson; Charlie Daniels; Michael Nesmith; MaLLy; Said the Whale

The success story of Fitz and the Tantrums isn't complete without mention of the Milwaukee man behind the curtain. Jeff Castelaz, president of the Warner Music Group label Elektra Records, signed the band in 2010 to an independent label he co-founded, Dangerbird Records. With a funky, retro-soul sound and the big bucks-generating single "Moneygrabber," Fitz and the Tantrums quickly became a live show favorite.

When Castelaz left, he encouraged the band's frontman, Michael Fitzpatrick, to move the group over to Elektra with him. The major-label support, coupled with an evolved soul pop sound on this year's sophomore album "More Than Just a Dream," led to an opening slot on former Elektra artist Bruno Mars' tour and an '80s-indebted single, "Out of My League," ending up at the top of the alternative singles charts.

Fitz will be joined by Capital Cities, a playful presence at Summerfest this year. The synth-surfing dance duo is best known for this year's breakout single "Safe and Sound." Its debut album, "In a Tidal Wave of Mystery," is consistently catchy and at times weirdly inspired, as on the Andre 3000-featured curveball "Farrah Fawcett Hair." Fellow synth-pop group Beat Club opens.

— Piet Levy