Sense of Spies
Do spies have any added value or just a fancy suit? Unfortunately I can not find any sense to use them
Forum Discussion
The radar dome is mostly the best use of a spy, since it'll make the enemy reveal the map for you.
Refinery/silos is somewhat useful to know the enemy's money, especially to see if it's worth using thieves.
Infiltrating a Sub Pen will give you access to the Sonar Pulse, a superweapon which reveals all submarines on the map for a short period of time.
