I have two 35 cm birkins - I think they are the perfect bag (I actually have three, a brown and a gold togo and a black clemence, but I am planning to sell the clemence and hope to buy a black togo. clemence is softer but I like the slightly stiffer togo given that I put papers and files in the bags). Once you have one, its trumps all the other bags. The size, ergonomics, etc are great. Light, not to soft not too rigid, can fit a notebook and a sweater but not look too big. Of course it doesnt fit over your shoulder, but it does loop over your arm, and it grips easily in your hand, so the shoulder thing is not really an issue. (when you need your hands free, thats what a kelly bag is for, I am told - I dont have one yet but am hopeful of having one someday).