Two of the highest-rated and talked-about summer series — “America’s Got Talent” and “American Ninja Warrior” — have set their season premiere dates. “America’s Got Talent,” the #1 most-watched alternative summer show for the past 10 years, will premiere on Tuesday, May 31 at 8-10 p.m. The series will shift back to Los Angeles this season. “American Ninja Warrior” swings back into action on Wednesday, June 1 with its two-hour premiere at 8 p.m. The series is hosted by Matt Iseman and former NFL player Akbar Gbajabiamila with Kristine Leahy serving as co-host.