Chicago rush last time I was there it took me 2hrs 45mins to go 9 miles! I do not go near d.c. anywhere near a rush hour period, it's faster to just route around an extra 50-60 miles, and like Ben said you can catch hell there anytime as nightime is the only time they can do most of their construction.
The 270/315/23 interchange could use reorganized for sure, probably the worst bottleneck we have. It will be fun when they go to rework it.