In the US, I don't think you can guage good/bad luggage tolerance based on airports, per se. It'll most likely vary by companies. For instance, in Atlanta, LH is very, very liberal but BA is definitely on the other extreme. DL is somewhere in the middle.

At some European airports though, FRA is a good example, where airport staff serve as the check in people for a number of different smaller airlines, you might find people who don't work directly for the air company to be very, very liberal. We've seen this to be true at both FRA and HAJ in Germany as well as AMS in Holland.

For those of us who travel a lot and with a lot of luggage, this is a pretty good thing to know...