Thousands of members of the National Black MBA Association will gather in Atlanta next month for their annual convention, reserving a combined total of more than 10,000 nights in Atlanta's hotels and eating in Atlanta's restaurants.

They would have been spending their money in Philadelphia, except that in 2012, worried about labor hassles and inefficiencies at the Pennsylvania Convention Center, the group canceled its September 2014 convention here and moved it to Atlanta.

Now they've rebooked for Philadelphia - in 2017.

John McNichol, the convention center's chief executive, said the group told him they had taken Philadelphia "out of the rotation," dropping the city from a list of preferred convention sites.

"[But] we had a daylong meeting with them," he said. "They asked very good questions, and we had very good answers."

The National Black MBA Association is one of a half-dozen shows that have agreed, either orally or by contract, to return to the Convention Center, now finally digging its way out of its reputation as a place with labor difficulties, costs and inefficiencies, and a leadership unable to manage those problems.

These gatherings, some of which also had dropped Philadelphia from their roster of convention cities, will spend a combined total of 114,314 nights in local hotels and generate $147.6 million in economic impact, according to the Philadelphia Convention and Visitors Bureau.

"We'll service any business," McNichol said, "but you always like the 'convert.' They formulated their opinions based on poor performance in the past."

Jesse Tyson, president of the National Black MBA Association, said Philadelphia had been a top pick - good location, fun city, matching demographics, and a strong local chapter.

But, during its 2003 Philadelphia convention, "quite frankly, the experiences on the positive side were more than offset by experiences on the negative side," he said.

"We didn't get treated like customers," he said.

Convention sponsors, who help cover the expenses of the gathering, felt mistreated, Tyson said. "It became too expensive and too risky in terms of relationships with our corporate partners."

Tyson said the Convention Center's new procedures convinced the group to give the city another chance.

Several key events occurred. The Convention Center Authority Board decided to hire SMG, a West Conshohocken company with national experience operating convention centers, to manage the site, starting in December.

Then, in May, four of the six unions that had been working there signed a Customer Satisfaction Agreement that changed work rules. Two unions did not sign by the board-imposed deadline and lost jurisdiction in the building. Their work was divided among the other unions and management staff.

"We are changing the paradigm, which is why today, they are opening their doors to listen to us," said Jack Ferguson, chief executive of the Philadelphia Convention and Visitors Bureau, which is charged with booking major conventions into the city.

"In the last 24 to 36 months, we've had those doors closed," he said.

Customers, he said, liked the city, but didn't like hassles imposed at the Convention Center. As centers opened and expanded in Washington and Boston, the city lost business.

That is changing, Ferguson said. "It's a better world than it was."

The Academy of Management, which held its convention here from Aug. 1 to Aug. 5, was one of the largest conventions to come to the Convention Center under the new arrangements. And, they've already agreed, at least orally, to return in 2021 and 2026, bringing about 10,000 attendees each time.

That means a combined total of 21,500 nights booked in hotels and $25.7 million in economic impact per event, the bureau estimates.

Taryn Fiore, an Academy of Management staffer who managed the show in 2007, when it was previously here, and in August, explained what changed:

"Every city has its challenges and we had some interesting challenges in 2007," she said.

The company that handled audio-visual hired a union crew at the convention center, but non-union audio-visual workers at hotels. Convention Center unions threatened to picket the hotels, she said.

The issue was resolved by hiring union members to work with the non-union crew.

Because her attendees enjoyed Philadelphia, its nearby hotels and restaurants, Fiore agreed to return this year. "Also, the walkability is great in Philadelphia," she said.

At this August's convention, her attendees encountered a protest - complete with an inflatable "fat cat" - mounted by the two unions that lost jurisdiction in the building.

Fiore said that the Philadelphia Convention and Visitors Bureau, led by Ferguson and Julie Coker Graham, executive vice president, helped her understand what to expect and provided extra help.

Inside, "it was the beginning of set-up, and to my surprise, carpet was already being laid in the hall when I expected it to take much longer," Fiore said. She said that wasn't the experience she had in 2007.

"It seems to me that the change is reflected in the work," she said. "It seems to me that the people who are working in the building are pleased with the changes."