But some people prefer a lighter, brighter score for the big day --- enter the harp.
"An organ can be a little overpowering at times," said harpist Carol Holsinger of Menlo Park. "A harp can fill all of those harmonies but still has a delicate sound to it."
The harp is also a flexible instrument, with many possibilities, said Margy Kahn, another Menlo Park harpist who has been playing at weddings for more than 17 years. It compliments other instruments well, but can carry its own weight solo, and works for both indoor and outdoor weddings, the latter being especially popular in the Bay Area, she said.
"It seems obvious that if you're having the wedding in a church with an organ, you use the organ," she said. "But if you're having your wedding in a garden, which a lot of people here do, then the harp is great," Kahn said.
Not only is the harp a relatively portable instrument that can project sound, but its more soothing tones compliment an outdoor wedding, she said.
Holsinger prefers to not play outdoors, though, because of the instrument's fragile frame and tendency to warp out of tune in direct sunlight. Outdoor playing requires an umbrella to protect from sun and rain. "The weather is more fickle than a room's temperature," she said.
The harp is also sonically versatile, and able to accommodate many styles with ease, from show tunes to world music, Kahn said. She has played weddings of all Irish music, and enjoys playing Chinese and Japanese weddings because of the way her harp can mimic traditional, Asian instruments. "I've had people come up to me and ask 'is that a Japanese harp?'" she said.
Often, what harpists play depends on what the client wants. Celine Dion's "My Heart Will Go On," or the theme from "Titanic" are favorites, as are songs from "The Phantom of the Opera," Kahn said.
Some songs translate better to harp than others. Jazz numbers, for instance, are often difficult for harpists, due to all the key changes, she added.
Holsinger is open to adapting the music her clients select, but her favorites are classical compositions, or hymns, such as "God of Our Life." She also recommends harp music for a unity candle ceremony, in which the bride and groom each light an individual candle and use them to light a larger candle, symbolizing the bond created in marriage.
It is important for the bride and groom to work together in order to bridge the gap between what they want and what the harpist can do, both women said.
"I think they should ask the harpist if what they want sounds good on the harp, and see if they can adapt it," Holsinger said.
Both Kahn and Holsinger began their study of music through piano lessons as children, and were introduced to the harp during college.
Holsinger began her training with the instrument almost on a whim.
"I was signing up for classes, and I saw a tiny piece of paper that said 'harp lessons,'" she said. "I thought 'I'll never have a chance to do this again,' so I did it. Within a year, I had my own harp."
Holsinger, whose husband, Kevin, is a fellow-harpist, now teaches classes on the instrument from her home. Her enjoyment of playing the harp, she said, comes from how much it requires of the musician.
"It's a full-body instrument. You're using your hands, and in my case with the pedal harp, the feet, and it's leaning on you, so you feel the vibrations from what you're playing."
Kahn was introduced to the harp while singing in her university choir, which was sometimes supported by the instrument. Later, she resolved to learn it herself, and when first playing weddings, she practiced for four hours a day to prepare.
"It's a challenging instrument, and I like the challenge," she said.
Because harp is sometimes a difficult instrument to master, Holsinger and Kahn say they need at least a month to prepare for the ceremony, though they say it's rarely a problem because most people plan weddings so far in advance. The bigger issue for brides and grooms, they said, is being flexible with their vision of the wedding.
"I played at a wedding in San Jose recently," said Kahn. "It had to be moved indoors into a rather small room, but it ended up being a great wedding. The father gave this speech and everyone cried. It was wonderful."