One thing that I hate about setting up a wedding cake outdoors is the possibility that the bugs will find it. A cake that's covered with gnats isn't a pretty sight. So when I set up the cake that was based on the Trevi Fountain I was interested in the net that they'd supplied for the purpose of keeping the bugs off.
This net hung over the cake table and covered it completely with netting to keep any insects and blowing debris off of it. It's similar to some canopies that I've seen in other places, but this one served a purpose instead of just being part of the table decorations.