According to http://en.wikipedia.org/wiki/World_Trade_Center#The_Twin_Towers The 108th and 109th floors of both towers were for mechanical equipment (also located approx every 30 or so floors throughout the building). The 110th floor of tower 1 was for tv and radio transmission equip. The 107th was an observation deck. Virtually all other floors were office space at approx 1 acre per floor.

I am blessed with the memory of having visited the World Trade Center in the 90's, before the first bombing attempt. It was an incredible experience. Looking up, feeling small. Then looking down and seeing it all . . . The South Tower had "Top of the World" on the 107th floor, an observation deck, open to the public. It provided an amazing view, all the way around. The ride up, inside a massive sized elevator was almost an amusement ride - sooo fast! "Windows on the World" was up top in the North Tower. It was known to be the highest-grossing restaurant in the USA, bringing in over 3 million dollars a month. This is from Wikipedia about the Observation deck and Windows on the World: On the observation deck. Although the majority of space in the WTC complex was off-limits to the general public, 1 WTC (North Tower) had a restaurant on the 107th floor called "Windows on the World", and 2 WTC (South Tower) featured a public observation area aptly named "Top Of The World." When visiting the observation deck, visitors would first pass through security checks added after the 1993 World Trade Center bombing. Next, visitors were whisked to the 107th floor indoor observatory and greeted with a 360 degree view of the New York City skyline, and exhibitions including a three-dimensional scale model of Manhattan, and a simulated helicopter ride around the city. Weather-permitting, visitors could take two short escalator rides up from the 107th floor and visit what was the world's highest outdoor viewing platform. At a height of 1,377 feet (420 m), visitors were able to take in a view of the North Tower and New York City unlike any other. On a clear day, it was claimed that visitors could see up to 45 miles (72 km) in any given direction. An anti-suicide fence was placed on the roof itself, with the viewing platform set back and elevated above it, requiring only an ordinary railing and leaving the view unobstructed. Windows on the World was an elegant restaurant known as a place for big celebrations, such as weddings. In its last full year of operation, 2000, Windows reported revenues of $37.5 million United States dollars, making it the highest-grossing restaurant in the United States. To read more about The World Trade Center, click here: http://en.wikipedia.org/wiki/World_Trade_Center

The Cantor-Fitzgerald bond brokerage firm was in floors 101-105 of the North Tower, they lost over 650 employees, and had by far the most significant loss of lives on 9/11. They are also implicated in conspiracy theories involving the timing of 9/11, since about $150 billion in bonds they held in trust were going to be called the next day, but all evidence of the bonds was lost. (http://www.the-catbird-seat.net/ChubbGroup.htm)

uh more offices.