Here's the Survival map:
The following is my two person strategy:
Both people sit up on the second floor in the spa-house each watching one of the stairs going up. Most of the enemies will go to player 1, but a fair amount will go to player 2.
Once you start to get 2 juggernauts or more (wave 9), as long as player 2 is at those stairs one of the juggernauts will drop down at the red square with the blue perimeter. If the juggernaut drops in during the beginning of the wave you can go place some C4 there, and no other enemies will spawn near there which will give you time to get back to the stairs, and you can most likely take out that juggernaut right away. Then if most of the enemies are going to player 1's position player 2 can work on the helicopter(s).
Both player should back up to the balcony together so that neither one gets shot in the back. Once you are overwhelmed jump off the balcony and run down past the equipment armory, and up those stairs at the end of that arrow. The outer edge of the map from 5 o'clock to 10 o'clock is all under cover, so you can stay safe from the helicopters while back up and taking out the juggernauts and other enemies, and once you get over to the left side you can loop back around while keeping decent cover if needed.
Don't ask me why, but if you sit up in the tower on the top of the map, none of the enemies will go up the stairs to the right, they all go to the left side of the tower, and that makes them fairly easy to take out during the regular waves.
Jugg/Helo waves: 4, 9, 14, 19, 24, 28, 32, 36, 40