To me: not full suit = biz cas. Obviously your industry/company may feel differently. I'm an engineer in Silicon Valley so I could probably wear a company polo with cargo pants and sneakers and qualify for "biz cas", but I choose not to.
RFX (or anyone else), do you get that back of the ankle rub with these? The last few pairs (not flyknits) I've picked up have given me a lot of trouble.
I'm gonna go with a hybrid between ghdvfddzgzdzg and Oski's last two fits this weekend. Navy linen blazer + white T + white jeans + those Loake jodhpurs.