I managed to get all the pics and then spent quite a while on further testing... but some of them still have me foxed since there are so many potential variables...
If a snapshot spawns and you miss it (after about six game hours) you'll need to close the game fully - back to the dashboard - and restart it.
"The Warden" seems to spawn pretty reliably in the warden's office after a few seconds on the very first time you load a prison after starting the game. If you don't happen to check his office (or her office - you can use any of the warden characters) in the first six hours then you'll miss it.
The solitary pics are really tricky. I had more luck using larger 2x2 solitary cells (unfurnished for "Bangup") but I'm having trouble replicating that.
I think I've had "Hygiene Matters" in several different rooms. It makes sense to have only one janitor and then follow him around. Remember to restart the game if you think you missed it.
For "Kitchen" try three or more cooks with meal variety set to High.
BTW I was doing some more testing today and got "Prison Life" with an 18 year old in a jail with only standard cells (bed and toilet). He was white though!