This is the sweet-savory burger of your dreams. The two meat mixture is key here: The sirloin and has clean, distinctive flavor, while the chuck provides fattiness and keeps the burger juicy.
Heat grill to medium (350°F to 400°F). Place sirloin, chuck, Worcestershire sauce, salt, and pepper in a bowl; gently combine (using hands). Shape mixture into 8 (5-inch) patties. Grill patties, covered, until beef is no longer pink in center, 5 to 6 minutes per side. Top each patty with 1 cheese slice; remove from grill. Cover with aluminum foil to keep warm.
Lightly coat onion and pineapple slices with cooking spray. Grill, uncovered, until grill marks appear and onion and pineapple are heated through, 2 to 3 minutes per side.
Spread 1 to 2 tablespoons Beach BBQ Sauce on cut sides of rolls. Layer patties, onion slices, and pineapple slices on bottom halves of rolls. Cover with tops of rolls.