I've seen somewhere that there would be up to 50,000 people working in the Twin Towers at mid-day (note: you'd need a much bigger bomb to actually bring down the towers, but I'll grant the premise). Yousef was trained in Afghanistan, so the response would likely focus there. The Taliban hadn't taken over yet so the operation would look like a combination of peacekeeping and hunting down Al Qaeda.
Domestically, the impact would be similar to 9/11 IOTL, possibly intensified somewhat by the higher casualty count. There would be no mid-late 90s period of sunny optimism, and pop culture would probably take a conservative and nationalistic turn. There would also be a backlash agains Muslims and Arab Americans at least as bad as there was in our timeline. The issue of terrorism would define President Clinton's first term, and he'd get a popularity boost similar to that of George W. Bush after 9/11 IOTL. Most of the controversies regarding Clinton would be more or less immediately forgotten, and it's likely that Democrats would retain control of Congress or even pick up seats. The economy would probably suffer and you could see a return to recession in the immediate aftermath of the attack, although there would be broad Congressional support for a stimulus bill, so growth would return by 1995-1996. An anti-terrorism bill with some similarities to the Patriot Act would have likely passed, which may or may not have enabled law enforcement to prevent the Oklahoma City bombing.