I don't know about lunch, but I often used a snack credit for breakfast to get a muffin or a little muffin-sized loaf of banana bread and then got coffee in my refillable mug. I seem to recall also seeing donuts and other types of pastries that would also count as a snack credit, and a small bowl of fruit also counts as a snack credit. I'm not a big breakfast eater, so something like that was perfect for me.
At the POR food court, you could get things like bowls of fruit (or individual pieces), bagels, large croissants, danish, large muffins, and cinnamon rolls as 'snacks'... when you consider all that you will probably be eating later in the day (appetizers, desserts, etc.), those items were plenty filling...