My commute is 19 miles, which is almost 3 longer than it needs to be in order to keep me off a 4 lane divided road that is too heavily travelled for my tastes.
Leaving from home I ride on 2 lane main roads through the suburbs, and I have a moderate climb half way through that slows me down. The good news is that the rest is very flat. Also in the middle 4 miles I deal with the worst traffic, but the worst is a short quarter mile on Dixie Highway (Aka Dixie Dieway). The last 5 miles to work are mostly weaving through residential streets.
I usually leave at 6am which gets me to work at least an hour early even after a quick shower, so I leave out an hour early to try and beat the traffic, which is light in the morning and heavy heading home. No bike lanes anywhere, so I am learning a ton about defensive riding!