For extra flavor, add smoked paprika or garlic powder to the tuna salad. Swap cheddar cheese for Swiss, provolone, or mozzarella for different tastes. Use day-old or thicker bread for sturdier sandwiches. Avoid soggy bread by draining tuna well and not overloading with tomato. For a lighter option, use Greek yogurt or avocado spread instead of mayonnaise. A panini press can be used for even grilling and crispy crust. Variations include spicy, herb-infused, crunchy, gluten-free, open-faced, and vegan-friendly options. Store leftover tuna salad in the fridge for up to 3 days and grilled sandwiches for up to 1 day.