On occasion I'll ride into school, which is 30 miles round trip, although I base this mostly on my schedule for that particular day and to a lesser extent the weather. To do that commute I have to traverse the entire length of Chicago's south side, which can get a little scary in parts, although I've never really had a problem other than flats. That's why scheduling is an issue, I don't want to ride through the hood after dark. Train = quicker and safer but not as fun.
This ride takes me about an hour or a little less each way, but I usually stop for lights.
I can't imagine doing 30 each way 2-3 times a week, I think I would be worried about getting worn out by the end of the day.
But most importantly, more power to you if you start doing this commute regularly. I have much respect.