I doubt that the CIA let anybody other than someone high up in the Pakistani Government or military know where they were staying or when they’d be there. So that means...well, someone high up in the Paki gov or military tipped off the terrorists.
About the same time frame, another bomb targeted a building supposedly used by the CIA. The story goes that the bomber blew up the wrong building.
The bell hops at that Marriot know more than the highest level officials in Pakistan’s elected government.
And that info was worth alot of money.
There is only so many Westerners running around Pakistan’s halls of power, the terrorists just have to target the white guys. Racial profiling works!