Let the holiday weekend begin! Here's a sampling of what's happening: the 9th annual "Troops in the Spotlight - billed as the largest Memorial Day event in New England - starts Sunday morning at Kmart Plaza in Hyannis and goes for 24 hours. Summer concert season is getting started, and the Cape Cod Melody Tentis opening its box office with a line-up of acts from Buddy Guy to Lily Tomlin and more. And Wellfleet Harbor Actors Theater stages the world premiere of Marina Keegan's play "Utility Monster."