Single. I've done 25min daily commute on the metro here in DC for 8 months or so. Not exactly the same, but in the ballpark.
I'm open to other suggestions, of course. It seems like Yokohama has lots to do, and it puts me much closer to Tokyo than if I live all the way down in Yokosuka. The commute is the obvious downside, but the quality of life seems like it might be better.
A few things
1) If I could live anywhere in the world, it would be a difficult choice between Tokyo and London. I've been to Japan about 30 times for work and pleasure, and will be heading back next month for a vacation. Some of the best quality food on the planet, interesting culture, dynamic, etc. The cities aren't pretty like Europe, but the countryside is wonderful.
2) I don't know about the Yokosuka area and military folks, but there's always a bit of tension between the Okinawans and the military. If that tension exists at your new base, just try to be civilian looking as much as you can. I don't work for the DoD, so civilian come quite natural to me...
3) Yokohama does have quite a bit to do, but nothing like Tokyo. That said, I wouldn't necessarily live closer to Tokyo. Honestly, how often will you be going into Tokyo? I imagine just weekends/holidays. Commutes in Japan can be a real PITA. Get on google maps and look at commute times between the base and where you may conceivably live. For work, we'd sometimes have meetings in the Yokohama area, but because of some of the roots, the trains were very local, very slow, and very few in number. At night, we'd have to run to catch the last train, which ended rather early. Sometimes we'd stay in Tokyo and commute down on the Yokosuka Line and have to switch 1 or 2 times. Ugh...
If you like beaches, living in Kamakura would be pretty cool. It's a "small town" by Japanese standards, but is also a top tourist draw. It takes less than an hour to get to Tokyo from there.