It likely took some big dollars to snag McCartney, who normally headlines stadiums without an opening act. He sold out two nights at Wrigley Field in 2011, and could easily fill Grant Park by himself. The undercard includes the fast-rising Alabama Shakes, who are primed for a breakout year as their latest album arrives in April. The Weeknd also brings an increasingly formidable reputation as an alternative R&B star, though his act didn't quite translate to the big stage at Lolla a few years ago. He also looks to be playing opposite McCartney, which could cut into his draw just a tad, don't you think? Those ready for a sweaty, soul-dance party shouldn't miss St. Paul & the Broken Bones. Brit James Bay won raves at the recent South by Southwest Music Conference in Austin, Texas.