A friend had a smallish wedding and decided on Whole Foods cake. But what they did was to buy a bunch of different cakes (premade/in the fridge case at WF), put them on pretty cake stands they found while thrifting, decorated with some edible flowers, then used those as the centerpiece for each table. When guests arrived at the reception, their tables were named according to the cake type: Carrot Cake, Red Velvet, Chocolate Ganache, Vanilla.
Instead of having a "cake cutting" cake, they went from table to table to cut the cake and take pics with their table's guests surrounding them. AND they encouraged their guests to trade cakes with other tables. It was a great idea as it really broke down the ice. Within minutes, people were mingling and trading cake slices and chatting and laughing. Plus, I got to try all the cake flavors. Awesome!