I was IFR on the way to Oshkosh one year. I know routing through C90 is always problematic so I just filed to GYY intending to cancel and go VFR up the lakeshore at that point. Somewhere around central Indiana I get a "27K would you like to go direct KELSI now?" I was about to accept that and then, "Hey, KELSI is about 40 miles past my destination." "Oops, you can go direct Gary now." He then offered the direct KELSI routing to a Belanca who was going west of Chicago. I detest having to go to KELSI. I am handed off to C90 at 10,000 one year and go through this: 27K: Is there any altitude I can request that will avoid me having to go to KELSI? C90: Let me check... (longish paus) ... nope. 27K: OK, here's what I'm going to do. Cancel IFR, Climb up 500' and go direct OSH. You can give me flight following. C90: That will work. The only problem with this is that they now are holding departures from both MDW and OSH as I pass in their climbs at 9000 to avoid me. Except they miss one. I'm watching an MD80 climb in front of me and then it descends. UA: I just got a TCAS RA. C90: Oh yeah, there's a Navion up there. 27K: I had him in sight. Now I know there's a mandatory report for the airline guy when he has a TCAS RA that causes him to deviate. I figure I'd send in a voluntary one in case someone actually cared when they read these things. Margy gets a call from one of her volunteers at the museum who happens to also work at the NTSB inquiring if we could manage to go to Oshkosh without scaring the wits out of an airline pilot. He turned out to be the guy who gets those reports.