Some completely unstructure jacket like the engineered garments andover (and it could be navy, grey black, I don't actually think it matters too much) is what I think would cover more of those "in between" scenarios than a navy blazer. Right, but we're covering the formality levels that the average person has to deal with. Let's take the OP's list of what he wants covered by this jacket: 1) "business casual" networking event: Above outfit would be fine, IMO 2) weekend theater or opera performance I would wear a suit for this. 3) going out to dinner at a nice restaurant with someone you want to impress, or at least look nice for Again, above outfit is fine in 99% of restaurants, for the hyper formal, the navy or charcoal suit will be better than a blazer anyway. 4) a classy holiday or dinner party again, above outfit. 5) graduations This depends on location, but I would prefer to wear a suit for a graduation.