Look at Betabrand and Swrve. Those two I'm at least familiar with and happy with their pants. At the high-end is Outlier which everyone raves about, but the price point is a bit steepfor me. Also - there is always a place to change if you're creative! Many have mentioned bathrooms. Conference rooms are also great if available and you can shut-out any peeping (e.g., pull the blinds on windows). As for cleaning up without a shower, I use baby wipes and coworkers haven't noticed anything in my many years of cleaning up at the office (or at least they haven't said anything).
A related comment - if you want to arrive relatively sweat free, a BIG plus is getting your bag off your back. Panniers FTW.
I mostly ride in my work clothes-- skirt plus bike shorts or skirt plus tights, extra layer of fleece lined tights for the winter. I'm sweaty upon arrival but usually am able to rebound in about 15 mins or so.
Always, always, alwayyyyys keep an extra emergency work outfit just in case, this is also good advice if you are prone to spilling coffee on yourself like me.
I second the panniers rec for avoiding back sweat!
I third the panniers, but as a cheaper alternative, one can strap any old backpack to a rear or front rack.
EDIT: and my unsolicited probably too late advice: do not enter that world!
The world of back sweat? What world???
The World of Business Casual :)
Everyone should just wear dresses and skirts, great ventilation!
Hmmm... I don't think my girlfriend would appreciate that I put on her clothes. I for sure rip them as I try to put them on. And her dresses, I don't think the zipper will close on my back.
I'll go to Uniqlo during lunch and try some skirts on ;)
...and if you have been prone to forgetting underwear (if you're wearing cycling shorts to the office and have a longer than abnormal commute), always keep a emergency pair of underwear somewhere in your bag. Only for emergencies!
They also help if some day, coworkers invite you to the new taco de cheese restaurant, and there's a communal Hershey squirt event - you'll come out winning because you do have emergency underwear.
Thank you for making me spit my coffee out on my keyboard
Days like today (and most of the winter) I just change clothes in the bathroom.
The only rough season is summertime because of how much you sweat.
How stylish are you?
Most of the cycling clothes meant to be worn at the office still look a little "techy"...they arent going to look/fit as well as your normal work/dress clothes.
Swrve is an option...but their stuff is more on the sporty side.
Im personally a fan of Outlier...but even their pants are noticeably "sporty".
Most people wont be able to tell because Chicago isnt really a stylish town.
IMO a set of panniers and a bathroom are your best commuting accessories.