My commute is about 20 miles round trip, give or take depending on my route.
It takes me 30-40 min to get to work, but 50-60 min to get home (more traffic and uphill). I don't consider it long, but I am used to it. I also don't like tacking on more than an additional 30 minutes to my ride in general (lovely spring/summer days being an exception) because then it cuts into whatever I have going on outside of my ride. It all depends on route or terrain really. More uphill = more time = longer ride, even if it's maybe just adding on another 2 miles.