A Cosmic Ray's in July 2008, I got strawberry yogurt as my dessert with my lunch. I did not feel like eating dessert and my son who was 14 months old at the time ate the yogurt (he LOVED it!). Later on, DH and I enjoyed sharing a HUGE cinnamon bun from Main St. Bakery and it was completely worth using the snack credit!!
Another time at DHS we ate at Pizza Planet and DH and I got apple slices as our desserts. They are packaged and easy to take to-go for later.
Many CS places also offer sugar cookies or chocolate chip cookies as a dessert option. At POP Century, I got a Mickey chocolate-dipped rice krispie treat as a dessert. They also had some really nice baked goods (cupcakes, cake slices, muffins, etc.) as dessert options which you could take and enjoy later.
Other options are chocolate cake with chocolate icing at the parks, strawberry shortcake, brownies sometimes. Or of course you could get ice cream if they serve it at that particular location if you feel like it and if you want your dessert right away.
At Epcot, if you are eating at the CS place in France they have TONS of dessert options since it is a patisserie. Norway also does, including school bread! You could get one of the wonderful desserts at either of these places as the dessert for your CS meal if you decide to eat there, no need to use the snack credit there. In Mexico at the CS location you could enjoy churros for dessert. They are fantastic! In Morocco, we enjoyed the baklava for dessert with our CS lunch.