OK, I'm going to go against the grain here and suggest a Part Time instead. I know you want a City and given your build it could just work...but I still think a man's broad chest (however tall and slim you are) might make it a tight fit if worn messenger style and I don't like how that looks. Also, because you are so tall and slim I think the size of the City may be disproportionate on you...in other words, the bag might look miniaturized against your build.
What I like about a Part Time for a man is this:
- it generally looks very similar to the City except it is wider and shorter and this shape's width would break up the tall thin line of your build and balance everything out more - does that make any sense, hard to explain
- the longer shoulder strap would certainly make it possible to wear across body AND it would look great
- RH or GH that's your choice. I say RH because it's more classic but still very edgy - I'd like to see man carrying RH and not GH, it's too distracting (and heavy!)
Hope that was clear, good luck!
Thank you so much I agree with you in many respects! And will def try the PT out!