If you and your fiance are thinking of serving a dessert course in addition to wedding cake here are two ideas you may want to consider:
1 - Select two dessert items and serve each one to every other guest. Since many of your guests will be couples and likely to share with each other, every guest will get to enjoy both desserts.
2 - Give each guest a tasting plate with two or three desserts in a smaller size so that each guest can enjoy a little bite of each one.
I like the idea of a dessert medley or dessert tasting plate because not everyone likes chocolate or pies or mousse. These two options allow you and your guests to enjoy several desserts and pretty much guarantees that everyone will find something on the dessert menu to eat.