Decades ago, when I used to urbex Detroit, I was wanting to go up the Penobscot and a middle-aged woman smoking a cigarette was outside the lobby looking like she kinda worked there. I asked her if she knew a way to get to the top of the building and she stated "Hun, I'm the building manager. You seem nice, let's go up to the top." So I, and I believe another SSPer, went up the Penobscot outdoor deck(s) and it had the best view of Detroit at the time. RenCen was under reno and there were no other observatories so yeah, it was pretty cool. The photos I took atop the Penobscot can be found here:
https://urbanohio.com/gallery/category/1116-aerials/