I’m in the minority on this forum and think the B25 looks cartoonishly small. I am similar in height to you and find the B30 perfect. I echo what others say and would take a B of any size to a casual dinner only. I’m of the belief that totes are not evening bags. I wouldn’t take out a Dior book tote to a formal event even if it was a mini therefore I also wouldn’t bring a B of any size. In the end, go with your gut. What size will you get the most use out of? I don’t find the 30 size heavy however I also live in a sprawling metropolitan where everyone drives so I’m not walking NYC blocks carrying it.