Of Their Own Accord: Follow the SGT into the building and clear it out. As you proceed through the rooms and floors, you will reach a room without walls, with snipers and rockets and enemies. Kill the enemies and use the Barret. Kill the RPG soldiers and pick up the javelin. Destroy the tanks and watch out for the choppers, they know you're there. After that, kill the enemies entering the building and head to the roof for extraction. Use the Machine Gun to kill infantry and defend the chopper.
Whiskey Hotel: Move through the tunnels and prepare to fight for the Whiskey Hotel. Don't try and rush, just wait for your team mate to say: Ramirez, move left, or squad move to cover. Move towards the downed chopper and then enter the West Side of the building. The following is close quarters combat and you won't have ACOG sights or Red Dots working, so take it slow and move forward. After killing a few enemies, you will have two to reach the roof but there isn't actually a timer. The time goes down as you get to certain points on the way up to the roof.