Combine pineapple juice, soy sauce, lime juice and sweet chili sauce. Whisk to combine; set aside.
Place skirt steak in one Ziploc bag and chicken breasts in the other. Seal tightly and place bags on a large baking sheet (in case of leaking the pan will catch the drips) and refrigerate severl hours or overnight.
Grill to desired doneness. I like to grill my steak for about 6 to 7 minutes on each side over a high grill. For the chicken, I usually grill for 7 to 8 minutes on each side, depending on the thickness. Right after grilling, transfer meat to a clean baking sheet and cover loosely with foil and allow meat to rest for 10 minutes before slicing.
Slice meat against the grain and serve with warm tortillas, fresh pico de gallo, guacamole, sour cream and the grilled onions and peppers.