Well I've had a change in heart from my recent beliefs.
Do the Circle Line....the current plan is solid, with some changes to their proposed loop routing and some of the station locations.
But most importantly...bring back the distributor subway plan!
Subway runs east-west under Monroe st from the Metra stations to Michigan Ave., branches north and south. South branch goes to mccormick place. North branch goes up under fairbanks, and eventually terminated in a 1-way loop going counter clockwise along fairbanks, Dewitt, Walton, Rush, Chicago, then back south on Fairbanks.
Brilliant in every way, just a tad, um, expensive. But the monroe part could largely be done via cut and cover, except for tunneling under the river, plus the costly transfer points at Dearborn and State.
See:
http://upload.wikimedia.org/wikipedi...or_Subways.jpg
http://en.wikipedia.org/wiki/Image:D...tor_Subway.jpg
http://en.wikipedia.org/wiki/Image:P...tor_Subway.jpg