Great question!
The play safe combo must best be exemplified by the Road Hole bunker, where depth and steep bank combine to force the issue there. The key bunker decision obviously is related to the answer to the question - "Can I get out in one shot?" I think most golfers are comfortable in any bunker they can see out of, and a deeper one - about six feet - starts to cause concern.
As to green depth, it really is a matter of degree on all shot factors, and the wind can change the same pin position caluclations daily, but I did hear Jack Nicklaus say once that 40 feet deep was about as shallow as he would go for. That has always been a good enough design criteria for me.......
Good players have such good distance control, and spin control, I think the amount slope of the green would also factor in - if a player can spin it back he might be more likely to go for it.
Many good players tell me that they are more likely to go for a tight pin into the wind, since they can judge how much extra club to give it, and they get more spin. Downwind is a more difficult shot, since the probability of spinning the shot in a tight area reduces somewhat.
I have designed a few greens with front bunkers and extreme depth. When the pin sets just behind the bunker, its similar to the (former) Augusta 13 tee shot theory - its harder to hit close to the creek when you know you have 50 yards of fw to the right. Sometimes, I think its harder to go for the pin when a larger area exists to bail out - especially if you are still putting a reasonable distance - than if you have an all or nothing shot. That is the kind of subtle shot decision that always creates interest.