First, we have a program that I started called Candid Council. Anyone can join, and there is no incrimination. It meets on an informal basis – as needed or periodically.
We also have a suggestion box. Anyone can put in a suggestion; it's confidential. It's by the coffee station, and only I have the key.
From my experience, I have junior staff come up and ask me questions. Some junior staff thought senior staff were not making the best decisions in terms of serving the company in the long term. They came to me for clarification and found it, confidentially and without starting a rift between them and senior staff. It ended up being a good learning experience for all of us.