Have had a fascinating tour around ATC bunkers and shared a pint with a few afterwards! It is more than ridiculous that it isn't as easy as it should be for ATCO's to sit in my jumpseat for a few flights .... I'd have every bloody ATCO flying with me at least once if I could...!
On the little occassions I've been lucky enough to have an ATCO in the cockpit, they often have fascinating stories to tell and can have a laugh (best of all they know when it's time to shut up!)