The hearings, which begin Monday, are closed to the public, but relatives who register in advance can watch on closed-circuit television at forts in New Jersey, Massachusetts, Maryland and New York City.
The suspects on trial before the military commission include Khalid Sheikh Mohammed, the self-professed mastermind of the Sept. 11 attacks.
An earlier round of hearings in May was also transmitted to viewing locations for relatives of the victims, survivors of the attacks, and emergency personnel who responded to the disaster.
Those proceedings were an exercise in frustration for some viewers, as the suspects refused to cooperate with the court, or interrupted proceedings to kneel in prayer.
Jim Riches, whose firefighter son, Jimmy, died at the World Trade Center, said he planned to view Monday's hearing at Fort Hamilton, in Brooklyn.
"It's difficult for the families. But it is 10 years later, and we have no justice," Riches said. "I just wish it was being broadcast throughout the whole world so everyone could see it, and could see what these guys are like."
The nearly 3,000 people killed in the attacks each have many relatives who could see the trial, but attendance at the first round of hearings last spring was light, with only a few dozen people at each site.
Riches said he didn't expect a large crowd for Monday's session either, largely due to the pain of reliving the attacks.
"A lot of people are moving on with their lives. A lot of people are just trying to forget about it and move on. But you can't, really. They aren't going to walk back in through the door," he said, referring to the victims.