I qualified with a 3:08 at the kind of, sort of hilly TCM. Had aspirations of sub-3, but our group didn't choose an indoor option - all training was outside in the dark, in ice and snow. Parking garages! Why didn't we think of parking garages! We ran 'Guthrie Hills', at the Guthrie Theater (before it moved to its current location), and a few other lesser known quad burners.
My experience at Newton Hills wasn't good, but not terrible until Heartbreak. It was 'littered' with bodies along the side of the road. That sounds awful - and it really was. Was a weird mix of "At least I'm doing way better than they are" and "Is that going to be me soon?"
Citgo. I ran with a GPS on my left wrist, and a pace chart taped on my right. I had heard about the relief of seeing the Citgo sign but for me, I already knew three things by the time I saw it. Where I was, how not-fast-enough I was going, and how much it hurt at the moment. Still felt like a slog - no Citgo boost for me. But, kind of like wrestling, I viewed it as short time in the 3rd and sucked it up.
It did start to feel better, and as the crowds got bigger and bigger into Boston adrenalin kicked in. Finished strong-ish. Crowds are great. And so are the foil sheets they wrapped us in when we finished - weirdly, that's the thing I remember most at the finish.
Since you're a Chicago guy, you may know who Hal Higdon is. I was lucky to be able to meet him a couple nights before the marathon. He was a legend in the running world at the time. We had a group pic taken with a few of us with connected backgrounds. Great guy, and one of the highlights of the event. As someone once said, "You meet the best people at marathons."
Good luck on your training, I've got nothing but respect for wrestlers who become marathoners. (As if one kind of punishment isn't enough!)