I've done several fam flights in the cockpit, and have always found them to be highly useful and a valuable learning experience, especially when I was training.
I learnt a lot about what the pilots do, and, importantly, what the aircraft can and cannot do. There's no point me giving the aircraft an instruction if it's not capable of doing it.
I also agree that it's a good idea for pilots to come into the control centre to see what we do. Visiting the 'other side' of the microphone gives much better understanding of the other's role.