The BBC has a disturbing story that senior Pakistani political figures were planning to meet at the Marriott Hotel on the day of the bombing but changed their plans at the last minute. While this might have just been a coincidence, more likely is that credible intelligence was received that the Marriott Hotel was being targeted:

“Interior Ministry head Rehman Malik said the president, prime minister and military chiefs should have been there. He told journalists “it would have been a great catastrophe”, but did not say why dinner plans were changed.”

What about those dead who were not considered sufficiently important to be warned away?