The team that I worked with was very helpful and let me learn through experience instead of handing me everything. The field experience was invaluable because it teaches you what you can't learn in a classroom.
The cost aspects of controls engineering. (personal preference, still am glad that I learned it).
Advice to Potential Interns
Don't expect everything to come naturally, you will get frusterated and you will fail, your employer knows this and your success will be based on whether you learn from those failures.
Advice to Management
I think the management team did a great job to include everybody in everything. I never felt once that I was lower than someone and this was a direct result of the management teams hospitality.