Here are our favorite snacks to use snack credits on at the four parks. I'm not positive that they are all still available and all still snack credits, but I think most (if not all) are.
Magic Kingdom
Main Street Bakery: Cinnamon Rolls, Key Lime Cheesecake, Smoothies
Main Street Ice Cream: Double Cone, Root Beer Float
Main Street Confect: Fudge, Chocolatears
Sunshine Tree Terrace: Floats, Shakes
Mrs Potts: Floats, Sundaes, Shakes
Aloha Isle: Dole Whip, Pineapple Float
Auntie Gravity's: Floats, Sundaes, Smoothies
Sleepy Hollow: Floats, Ice Cream Sandwich, Funnel Cake
Adventureland Carts: Nuts, Egg Rolls
Epcot
Fountainview Cafe: Waffle Cone, Shakes, Double Scoop Cones (get a bowl and split between two kids), Floats
France/Boulangerie Patisserie: Many things
France/Crepes des Chefs de France: Many things
Germany/Sommerfest: Strudel, Black Forrest Cake
Norway/Kringla: Cappuccino Cheesecake, Almond Pretzel
Canada/Promenade Refresh: Smoothies
Refreshment Port: Dulce de Leche Sundae
Land/Nut Cart: Pecans, Almonds
Food samples at Food & Wine Festival!
Hollywood Studios
Backlot Express: Marble Cheesecake, Strawberry Parfait
Writer's Stop: Iced Mocha, Carrot Cake
Dinosaur Gerties: Waffle Cone, Ice Cream Sandwich
KRNR: Smoothies, Waffle Cone
Min & Bills Dockside: Shake
Oasis Canteen: Funnel Cake
Starring Rolls: Banana Split Cake, Cheesecake, Butterfinger Cupcakes, Peanut Butter Cupcakes
Animal Kingdom
Anandupur: Chicken Fried Rice
Dino Bite: Sundaes, Shakes, Floats
Flame Tree: Key Lime Pie
Harambe Fruit: Pineapple
Kusafiri Coffee: Cupcakes
Tamu Tamu: Shakes
Safari Egg Rolls: Egg Rolls