Look here:

https://www.chicago.gov/city/en/sites/covid-19/home/emergency-travel-order.html

If you are coming from a State listed, you "shall be subject to mandatory self-quarantine for 14 days or the duration of the person’s presence in Chicago, whichever is shorter".

Whatever that exactly means, it sounds like you would not be running around the hotel, socializing. (Incidentally, Westin requires wearing of masks in all public areas of the hotel.)

This list is updated every Tuesday to go in effect the following Friday. So, it's a crap shoot each week if you are deemed ok or not. You could make plans but get "quarantined" just before Expo.

For those who fly directly into Chicago, add $200+ bucks for refundable fares. If you drive there from out-of-state, here's info from a list updated August 12, 2020:

"Illinois: There are no statewide quarantine orders, but Chicago has its own two-week quarantine mandate for anyone arriving from a long list of states that have experienced “a surge in new COVID-19 cases.” Quarantine is necessary even if you have proof of a negative COVID-19 test.

Penalties: Violators are subject to fines of $100 to $500 per day, up to $7,000."

https://www.aarp.org/travel/travel-tips/safety/info-2020/state-quarantine-guide.html