I personally don't like leaving my passport or extra cash behind so what I did was i got pouch that attaches to my belt and goes down the inside of my pants. I cant get it off without undoing my belt and the loop has cabling ran in it to make it slash proof. Def made me feel secure knowing I knew were all my important info was at all times. I then carried a wallet with about 50 euros in it to use as daily spend. If I ran out and needed more I just pulled more out in a private bathroom. This way if for some reason I did get pick pocked I was only out a little bit of cash and even then I never felt a real threat.

I do agree with you that there are certain places where you cant help but be bumped into. I personally wasn't worried about the Sistine Chapel but Trevi especially at night I kept a good awareness around me. I did laugh though when I watched people read the pick pocket warning sign and the first thing they did was check their wallet. I had to make a conscience effort to not do the same the first time I saw it.