The Macro would be good for ring shots. Not sure what the CA is like on the 100mm, but the 85mm is fairly strong, so shots of the bride outside might benefit from using the macro rather than the 85mm as well.

And I can tell you now, people will suggest renting the 17-55 to replace the 15-85 for anything indoors.

Having never shot a wedding, that's about all I can add.