Hiring a good photographer and DJ (though not the same person)

The two people that make our wedding day run smoothly (because we were pressed for time due to a combination of weather and venue) are the photographer and DJ.

We had the wedding and reception in the same place (a botanic garden) which is another thing I'd recommend.

Hire a photographer that's (preferably) a friend, or at least someone you've negotiated all the details with in advance. (Ours, for example, knew ahead of time I wanted the high-resolution digital images at the end, and we didn't have to argue about it after the fact.) Between the ceremony and reception, our photog herded my wife and I around the garden, taking the first pictures of our married life together, while plying us with scotch. He also got candid photos of friends and family that we still cherish -- especially family that's no longer with us. Absolutely 100 percent worth every penny.

Second: For the half hour or so that you and your spouse are getting your pictures taken, you need someone else to manage your guests, and that's the DJ. A good one will make sure they get from the vows place to the reception place and play your favorite music along the way, and let them know where the food, drinks and bathrooms are. The DJ is absolutely key to having everything run on time.