I haven’t driven in too many cities outside of my humble Boise-area locale. We have our share of bad drivers like just about anyplace else. The only other comparable city I have driven is Wichita, Kansas, whose drivers were about like they are where I live.
I have been in Seattle, though I have never driven in the city. The traffic is pretty heavy in a lot of places and it seems that aggressive driving is a must if you to get anyplace. I see more and more aggressive driving habits around here as the city gets bigger and more crowded.
The worst driving I have witnessed would have to be in Mexico City. Lane markings are meaningless and people just drive wherever there’s enough space for their cars to fit. We were in a taxi and the driver would just pull up in between two cars which were in marked lanes upon arriving at the light. It was quite a knuckle-whitening experience riding around in Mexico City.