To the old man who put his hands around my waist
Next time, don't. I realize you were trying to get through and I was perhaps in your way (and my cellphone, I admit), but since you were at least a foot taller than me, you could have put your hands on my shoulders to gently push me aside. Quite frankly I wonder if you were trying to cop a feel and only stopped because I reacted quicker than you expected.
I wish I had taken a picture, but I was so taken aback and ready to give him a two fingered salute if he looked up. Ugh.

wow, I would much rather have
wow, I would much rather have someone move me by my waist. I would NOT want someone reaching up towards my neck and shoulders..
I would have a problem with someone grabbing me below the waist or above the armpits..
Some people are very wierd about touching, and would feel violated over any kind of touching..
IMO, there is NEVER any good
IMO, there is NEVER any good reason to go in with both hands. if you need someone to move, start with an "excuse me." if that doesn't work, my next tactic is a very light tap on the side of the shoulder using a finger or two. definitely NOT with two hands, definitely not a grab and definitely not sexual.
If I absolutley have to touch
If I absolutley have to touch someone to get their attention I go for the upper arm or the elbow