Calla lilies look absolutely beautiful when used in a shower or cascade bouquet.
Here you can see a stunning shower bouquet of white calla lilies from www.wedding-flowers-guide.com
I think they look very classic and elegant when used on their own but you can use them with other flowers effectively.
For more information on different bouquet shapes visit http://www.wedding-flowers-guide.com/wedding-flower-bouquets.html