Unless last-minute delays develop, the Hyatt Regency Hotel will open its polished brass doors for business tomorrow afternoon by holding a press conference in its completely remodeled lobby.

Hotel workers have arranged several hundred live plants--yellow and lavender chrysanthemums, philodendrons and palms in vat-sized clay pots--around the edge of a terrace restaurant overlooking the lobby, and along the 120-foot length of the redesigned second-story terrace walkway, a span hotel officials insist is safe and sound.

No clues remain of what happened at 7:05 p.m. July 17 as the Steve Miller Orchestra played the opening bars of Duke Ellington's "Satin Doll."

Gone will be any hint of the disaster that killed 111 people when two suspended skywalks plunged to the crowded lobby floor during a popular tea dance. One hundred eighty-eight were injured in the bloodiest mass disaster in the city's history. Two of the injured died later--a 32-year-old first grade teacher and a dentist, 63, who had gone to the dance with his former wife.

Officials of the city, Hyatt Hotels and Crown Center Redevelopment Corp., owner of the hotel, have agreed to treat the reopening with as little fanfare as possible, to attempt to reassure the public of the safety of the $50 million, 750-room hotel, which first opened in mid-1980.

"From other people's experience, we've seen the best way to handle it is not to talk about it. It'll go away," says Jim Smither, sales director for the Greater Kansas City Convention and Visitors Bureau. "People forget it. Just don't make a big deal out of it."

At 11 a.m. today, two committees of the Greater Kansas City Chamber of Commerce will issue reports on the fitness of the hotel to the city council.

About an hour after the hearing at City Hall ends, if the chamber says the hotel is safe, as expected, the president of Crown Center Redevelopment Corp. and the hotel general manager will answer questions in the lobby. They will report what it cost to redesign the lobby by replacing three suspended skywalks with a terrace 16 feet 7 inches wide supported by five concrete pillars resting on the foundation.

Then, if all goes by plan, the first convention guests of the Hyatt's fall season can register. They are 50 members of the National Ornamental and Miscellaneous Metal Association, followed by 1,500 members of the Missouri Restaurant Association and a two-day meeting of the Federal Reserve Bank of Kansas City. The American Association of Trial Lawyers backed out of a commitment for a 1982 convention, pleading possible conflicts of interest because members could be handling some of the civil cases stemming from the accident.

Nearly 120 lawsuits seeking more than $2 billion in actual and punitive damages have been filed in Jackson County Circuit Court and U.S. District Court here. Missouri residents file in state court, out-of-state plaintiffs in federal court.

"I think most lawyers believe most cases will be settled out of court," says Circuit Judge Timothy O'Leary. "But some will probably go to trial."

Perhaps the greatest impact of the Hyatt disaster has been on the survivors. One person whose father was killed under the skywalks has taken up the personal cause of inspecting buildings. A middle-aged woman who was standing on the hotel's third skywalk--the one that didn't fall--required counseling before she would go into even a small shopping mall, and needed additional coaching before she was able to walk across a suspended walkway in a larger shopping center. A retired engineer has forced himself first to drive by the Hyatt, then walk by, then listen to "Satin Doll" on a stereo until he could control his fear.