Can a charged 120v high voltage capacitor really kill you?
You are right that 3) is the most risky situation, and I (and I think most other contributers here) have experienced 2) (not with that sissy 120V you americans use, but with the european 220V that real men use...) and survived with only a tinkling sensation, and in theory 1) should be harmless.

But that depends on the situation being exactly what you think it is. And we never make mistakes, do we? There never are any unexpected leakage paths, especially not across you skin because you were sweathing from concentration?

I can cross the street in front of my house with my eyes closed for 10 times and I will (probably) survive unharmed. That doesn't realy make it a good idea to do it an 11'th time...