It was the wedding dress of the decade. The silk taffeta, the tulle and the lace — with hand-embroidered pearls and sequins — reflected the decadent 1980s from the top of each puffy sleeve to the edge of the 25-foot train.

Princess Diana would go on to become a noted fashion icon, but in 1981 it was her fantastical wedding dress that made the ultimate debut.

Soon the world will watch another princess make her way down the aisle and into the annals of royal fashion icons. Details of Prince William and Kate Middleton’s royal wedding have been leaked since their October engagement, including the rumor that Sarah Burton, creative director of Alexander McQueen, has been chosen to design her wedding dress. McQueen officials have issued the obligatory denials.

But really, why does everyone care so much about the dress?

“Royal weddings have always set the trends in the wedding world,” said Karina Timmel, executive editor of Atlanta-based Getmarried.com. “The dress is such a focal point for personalization. The dress can be used as a muse for the cake, the invitations. It kind of all starts with the dress.”

Last month, designers of Princess Diana’s dress revealed they had a backup dress, just in case details of the original were leaked. It’s a lot of subterfuge and planning for something that can be worn only once in your lifetime, but even brides not marrying into the royal family say the dress, more than anything, can make or break a wedding.

“I think it sets the tone of the wedding,” said soon-to-be-married Maggie McElhannon, 32, of Buckhead. “You do everything else for the wedding based on the dress.”

Beauty over budget

For her April 30 nuptials to Bryan Combs, 40, McElhannon knew she wanted a dress with a vintage feel and chose a mid-1800s farmhouse for the ceremony.

She arrived at Wedding Angels Bridal Boutique in Roswell with a party of six and three requisites: “Fitted, long and lace,” she said. After trying about 10 to 15 dresses — average for most brides — McElhannon realized she had found “the one,” though it was slightly over budget.

That’s when she learned an important lesson. “Once I put it on, I knew that was the look I was looking for and the budget was just going to happen,” McElhannon said. “I’ve watched enough TV to know that when you put on the dress you want, you throw the budget out of the window.”

Or as Jacqueline Westney, owner of Wedding Angels put it, “There is lace ... and then there is lace.”

In McElhannon’s case, her lace was about $800 to $1,000 pricier than the lace in her budget. (And yes, there is a visible difference.)

But Westney pointed out that many brides find exactly what they want at budget or below. Wedding Angels has gowns priced from $500 to $5,000. They stock popular designer brands, such as Jim Hjelm, as well as exclusives such as Eugenia Couture and Lucca Bride Collection of Denmark.

Having worked with more than 10,000 brides in the boutique’s 12-year history, Westney has seen many brides agonize over the right dress.

“It is really the only time in life for the average bride that she has so many sets of eyes on her at one time,” Westney said.

A weighty garment

The right dress makes you feel beautiful. It helps create a lasting memory that survives for decades in photos and video. The right dress may even be passed from one generation to the next.

That’s a lot of responsibility for a single garment.

“There is a very strong emotional attachment to it,” said Heather Levine, senior fashion editor at Theknot.com. “It is something so heavily steeped in tradition. When all eyes turn to you, you want to feel amazing. You want this day to be the best you’ve ever looked.”

One of the first things a bride does after getting engaged is make an appointment to try on gowns, Levine said. “You may try on and find your gown before you have purchased invitations, or finalized your venue. If that is the first thing that you choose, it is really going to drive everything that you do,” she said.

So it’s understandable that you may make some adjustments to accommodate the right dress.

With the average wedding costing about $27,000, the dress, on average, can consume 4 percent to 10 percent of total funds. “It is really different for each bride,” Levine said. “One bride may spend $10,000 on a dress and only serve wine and beer, another may insist on an open bar and spend a little less on the dress.”

The buying experience

But according to a survey from Theknot.com, 63 percent of brides are still going to local bridal salons and boutiques for a dress, with about 55 percent making a purchase there, Levine said. They may surf the websites of specialty retailers for ideas, but when it is time to buy the dream dress, the experience is part of the dream.

“Having your bridesmaids or mom or grandma come with you to purchase the gown and have that ‘aha!’ moment when you find the one is part of the experience,” Levine said.

Which is how McElhannon ended up at Wedding Angels with six people and six opinions. Looking back, she admits that may not have been the smartest move.

“The more opinions you have, the more your own gets lost,” Westney said.

But McElhannon managed to navigate the myriad opinions and find her own, just by listening to the dress.

“I was surprised at how much the right dress felt right and how attached to it I was when I put it on,” McElhannon said. “I was surprised by how strongly I felt.”

And princess bride or not, that’s all that really matters.