TNgypsy, I'm 5'9" with a medium build, but busty.
I have a large regular cherry Cuir and medium Cuir Cody. While I love them both, I think my medium is a better 'fit' and that's because of the strap length. The Cody's strap measures 40 inches from hardware to hardware, which gives a 20 inch drop. That works well for me, even with being busty, and the medium is a very nice size.
By way of contrast, my regular Cuir strap is 34 inches from end to end. I can't even begin to consider that a crossbody.; it hits me just under my chest and looks so ridiculous.
Longchamp is not great in my experience about listing strap length dimensions, which is bad for us tall folks. I think the ideal is to either check the bag out in person, or inquire about length before ordering.