I commute as often as I can - 7 miles one way if I go straight there, but we have a lot of bike trails around here, and a state park, so I usually increase that to 11-15 miles one way. If I have time, I'll take my time and a longer route home, increasing that leg to about 20-25 miles for a 30+ mile day. But work often requires me to drive in, so some weeks I don't get to commute like I want to.
I ride every Saturday morning, as I'm a group ride leader at the LBS, and those are typically 25-35 mile rides depending on the climbs I throw in.
I had a 300 mile goal for last month, and got 325. My goal this month is 400 miles, and I'm pretty much on target. This week was tough, and I only got 75 miles in. I'll make it up

Like others have said, just ride. Any time on a bike, is a good time for me, even if it's only 30 minutes. I'll ride to run errands just to ride.