Actually, the one that impresses me is snagging CKOC in Duluth. They don't (or aren't supposed to) throw all that much juice to the west. When I'm in Ontario, I usually lose it around London, ON daytimes. That's about 100 miles, if that.
BTW, my own personal best mid-winter daytime catches....
WWL in Moline, IL at high noon (I'm going to guess about 800 miles). WDGY in suburban Chicago. That was on 1130 when I was in high school and before WISN moved to the freq. Only about 340 miles, but (supposedly) in something of a null. I've also caught CHWO here a couple of times (about 500 miles).