I also commute. I have lived as close as 10 miles to work and as far away as 20 (one-way). I find it takes me roughly twice as long as the same route in a car, but the workout is then done. It's already wasted time in the day, you are just using it to save money on gas and get a workout in. Example: I get home at 615 when driving, I'm home and showered by 715 cycling, but have 40 miles for the day. That's with a 20 mile commute each way, obviously the gap is smaller on shorter commutes.

I don't know how I would get the mileage in if I had to do 2 hours after I got home, I wouldn't be done and showered until like 9, and going to bed at 1030 that would suck.