You should contact the City's attorney to see if you can work something out. If you want to avoid personal liability you will probably have to file bankruptcy.
Go speak with a bankruptcy attorney, preferably one who is familiar with Chicago real estate ordinances. Maybe something can be worked out with the city. Otheriwse, like you said, you might have to file bankruptcy.
From personal experience I can tell you the City is in a huge pickle with abandoned properties, both buildings and vacant lots. While buildings are worse (vandalism, drug houses....) vacant lots accumulate debris, grow weeds, etc. I have a client with scattered site properties like yours in the City and are in the same position; we've reached out to the applicable aldermen to see if any charitable organizations in the neighborhoods might want to take donations of property for future purposes and haven't even had the courtesy of responsive phone calls. If you can't personally afford to keep these properties up yourselves or comply with the City's requirements, then indeed you should consult with a bankruptcy attorney, but you can also contact a real estate auctioneer but if these are scattered sites you're right, even an auctioneer may find it not worth their while except, perhaps, as a bulk sale.