I did a 6 month field rotation at my first job, so I got to go see the products in a bunch of different environments, which was very cool. The literal "coolest" was in Appleton, WI in February. Had to borrow a block heater in the morning to get the rental RAV4 started... The best was ft Lauderdale, FL a couple weeks later, and only being allowed on site from 5-10pm meant a lot of beach time!
We also had some panels installed in the high freq trading server room at a large bank. Anytime I worked in the room, I was always escorted by armed security and a senior IT person, to make sure I didn't break the money printing machines.