Factory tours were the best. A Coca Cola bottling plant in Bangkok and a Del Monte canning facility somewhere around Fresno in the 70s were like serious high points of my childhood. It's probably an OSHA/insurance "NO!!!!" nowadays.
We did two that I think were staples in the DC area - Embassy Dairy, that tour started at a farm in Montgomery County watching cows get milked, then on to the processing plant which, while spotless, had a sour smell to it. But the number one tour was the Wonder Bread bakery. Oh the smells, fantastic. Then at the end of the tour they handed out a little mini-loaf to everyone and we were tearing those things apart on the bus eating them.
Not unlike how I felt at the conclusion of my Jameson's tour just over a week ago.