Oh, you can also have assault on president.. for example the president getting out of the limo and moving toward the hotel, then one guy with sniper try to kill him..he fired 2-3 times and hit the president then some FBI agents remain with him, the other running toward the building where they heard a shot or something like that..
also bank robbery would nice

2-3 guys have hostages in bank..then someone call noose etc..

I am full of ideas, perhaps it is foolish to suggest 4-5 ideas.. but if you think that some ideas are stupid don't put them on list. ^^