As part umpteen of my Midwest tour 2015 (I should have sold tickets!) I am currently at a writers conference in Indiana. My go-to for this sort of thing is nice jeans with an interesting top and a jacket or cardigan in case of overactive ac. In my area, dresses or dress pants would be too fussy unless you were a presenter. I'm definitely in the minority here though. Very few jeans on either gender even on the young. It's like everyone decided that since it's a conference that denim was too casual - but there are plenty of knit tops and t-shirts. And on the women, knit dresses that I wouldn't wear to an office; they have more of a 'casual dinner out' or weekend feel to me.
The New York agents and editors, on the other hand, are in east coast casual - no suits but everything very preppy and fitted. Not so much black since its July, but lots of serviceable neutrals. The Midwesterners, in comparison, are much more colorful. No ironic normcore here; everything is actually practical but in fun colors.
tl;dr: I am in denim withdrawal, and I feel like I've got 'west coast interloper' written all over me.