Fred&Wynne chose to have a first look on their wedding day... I can't say enough about doing a "first look!"
Besides being the modern, hip thing to do, it offers you time before the ceremony to see each other, spend an intimate moment together, and just relax a bit. Weddings can be stressful and the momentum just keeps building. A "first look" gives you that little refresher time to breath, relax, and be with each other.
Not to mention, it allows for some great family, wedding party, and just-the-two-of-you picture time!
Besides. When she's walking all pretty down the aisle, I'm blocking the view for him as I'm snapping away.