Cut mango and pineapple into bite-sized pieces. In a small bowl, whisk together peanut butter, cream cheese, and soy sauce, set aside. (If you used canned pineapple, you can use a little of the pineapple juice to thin out the sauce.
Chop spinach. In a large bowl, add fruit and spinach, toss together with the peanut butter mixture. Fill each pita with mixture. Serve or wrap up and store in the refrigerator.