When people meet with me, they have many questions because, often times, they've never done this before (interviewing a DJ for a wedding). When you're a guest at a wedding, you approach it differently than as the host. One of the most frequently asked questions I get is:
How long should my wedding be?
Sometimes the answer to this question is dictated by the venue; One popular spot in this area only allows 4.5 hour rentals total (not counting time to setup), most likely due to the fact that there is a curfew in that town. However, other venues practice a "pay to play" approach, which is almost a charge-by-the-hour arrangement. Nonetheless, your DJ and other vendors likely are contracted with a certain start and end time. How do you know what that should be?
The first thing to think about, as far as hiring a DJ, is if he/she will be playing the ceremony as well as the reception. Most ceremonies last 30 minutes tops, not counting if you have any prelude music as guests are entering and being seated.
After the ceremony, while the newlyweds are whisked away by the photographer, guests enjoy a cocktail hour, followed by the grand entrance of the bride and groom. The reception starts at this point with first dances, toasts, maybe a blessing, then dinner. The amount of time dinner takes is usually dependent on if it's served or buffet-style and the number of guests, but in most cases, this too lasts no longer than an hour, including any cake cutting, parent dances, and bouquet/garter toss.
Then the dancing gets underway! It's good to know, though, if your guests are the "dancing crowd" type or not. While some people might want to party until the break of dawn, keep in mind that they have been there most of the day already by this point, and if it's summer (and if you're outdoors), they may be hot, tired, and perhaps have a few drinks in them too! While some guests may be staying close by for the night, others will want to hit the road before it gets too late.
With all this mind, you don't want to overdo the dancing portion of the evening. A great DJ can keep the dance floor packed, but he/she cannot do anything for tired feet and the heat created out there. People get tired, especially the bride and groom after a whirlwind of a day.
There's nothing worse to me than seeing only a handful of people when the last dance rolls around. This should be the grand finale and send people out with a bang, but when the place is mostly empty at this point, it's often due to the fact that the reception has gone on too long. "Leave them wanting more" is a motto I like to apply to my DJ sets.
In total, weddings should be between 5-6 hours, the latter amount if there's a ceremony with prelude music. If the DJ starts right when the ceremony begins, aim for 5.5 hours. No ceremony? Keep it between 4.5 and 5 hours. While most any DJ can play for as long as you want, make your dollar go the distance with keeping the amount of time to a manageable amount for all your guests.