Wow. I don't mean to be a jerk about this. Sure, it's something all of us would probably love to have a chance to do. But I can't imagine any bank that would allow any of their customers (or friends of an employee) to have authorized access to their vault just to "look for collectible currency & silver coins." Or to even just go behind the counter to look into the vault. If this truly is an option at a bank, I guess the laws, regulations, and rules regarding bank security/access and the public isn't what I imagined it was.
I go into one of my bank's vaults two or three times a year. That's where my safety deposit boxes are. :>)
Related story I just have to tell. Back in the 40's and 50's, "Mr. Phil" [full name Philpott - I don't remember his first name, everyone just called him Mr. Phil] had access not to just a bank vault, but the Federal Reserve bank vaults. [Of course, he was president of the Texas Bankers Association - that might have had something to do with it.] He managed to pick up things like $50 Federal Reserve Bank Notes. My brother once bought some notes from him. He asked Mr. Phil if a check was OK, because otherwise he would have to use his beat up $1000 bill that had taken him years to get out of circulation. Mr. Phil said of course he'd take a check, but they didn't allow beat up money like that in Texas. He waded it up and tossed it to a teller at his bank, said deposit this. She said "Yes, yes Mr. Philpott." Then he said "I'll replace your $1000 bill with a nice crisp one - which district do you want?"
About 10 years ago I worked with a local bank in writing the bank's history. They still had sheets of their own Nationals in the vaults which continued to be carried on the books at face value.
Did you make the slightest suggestion to them about purchasing one? It would have been worth the try.