Not all at once...
Don't over indulge and take on tasting all the cakes in one day. Most cake suppliers offer 4-5 types of cakes and 4-5 types of frostings and fillings. Even for someone with a sweet tooth, this just might be sugar overload. By the time you get to your third tasting, you just might never want to see another slice of cake again. Spread your tastings out over a couple of visits.
It is also a good idea to start with the lighter, airier cakes (like angel food cake) and progress through, ending with the richer, denser cakes (like dark chocolate).
Ask how big the slices are, to get an idea of how big a cake you’ll need to order to feed all of your guests. If their idea of a slice of cake is much larger than yours, you can easily order smaller.