DC and NJ-NYC area are tied for the worst for me. I hate when there is one of those huge backups.... I'm all excited to see what the hell I have been sitting in traffic for an hour... it ends up just some damn cop sitting in the median during rush hour.
Or the people who would rather die then let you merge when one lane is closed.

I also like the H2 driving soccer mom on the highway who inadvertantly changes lanes as she adjusts her hair and makeup.
I also enjoy motorcycles doing wheelies on 95 during rush hour. Another favorite for 95 in NJ is debating whether to take the regular or the truck side of it only to find out there is an accident on the side that your took.
2nd on my list is South Jersey shorepoints area during the summer. Forget about getting anywhere on friday night and sat morning. Suburbans with luggage carriers on the roof, S-class Mercedes packed with old people, Superdutys with 30ft boats or waverunners and high-schoolers in their Wranglers all packed onto the same road. I almost forgot about the sea of minivans also.