I have a 6' cased opening in left rear of my control room. The opening goes into a largish room with wood floors. I'd like to keep reflections from that room out of the control room. I was thinking of applying a curtain to both face of the opening.

Will the curtains completely fix my problem?
If so, then what material would be best?
Any thoughts on a better solution?

A curtain might help, but a door is a better option. You can buy light-weight folding doors that hang like a curtain, and that might be a good compromise if a full door is not practical.