Monogram lighting is great. If you place it on the floor it will become obscured during dancing so it's probably better to place it on the wall behind the head table or the couples table. Some more information on gobos. There are glass and metal ones, depending on your design will dictate the right gobo. Here is an explanation of them with pictures.
Monogram Lighting and Design for Weddings
Another great place for gobos is gobosource. They are quick and for glass gobos the cheapest.