My commute is a little less than 25 miles, round trip. On top of that, I'm an old f*rt (will be 60 tomorrow). I enjoy a century or 200k ride on the weekend, but a ride of that length after 125 miles during the week seems to be a bit much.
If I'm planning a century or more on the weekend, I'll usually skip one commute ride that week. If it's a century or more where I'll really put out a hard effort, like the Hotter 'N Hell Hundred, I usually just commute three times that week. I take an unplanned day off the bike here and there when my body tells me it needs it, too.