My thoughts: At the beginning of my suiting life -- which is to say junior year in college -- I would only consider ventless. I thought single vented was old-manish and double vents too "odd." I liked the obsessively clean line through the hip that only ventless jackets can really give you. I stayed this way for several years. About 18 months ago I started to like how a vented jacket "skirts" away, especially when you walk -- you can keep the jacket buttoned and you still have beautiful movement in the bottom of the jacket when you walk. In addition, I saw how the double vent broke up the line between the pants and the jacket, making the suit seem less like a uniform and more like two separate parts working perfectly together. I at first liked the single vent because double vents just felt too stylish, if that makes sense. I once purchased a terrific Lubiam flannel suit for $200 and took it back because it was double vented (it was fused, but still it was a terrific suit -- Lord how I wish now I kept it, as I need a flannel suit for winter). Even after I started upon this board 8 months ago, I still preferred single vent. It was only until about four months ago that I got comfortable with the concept of the double vent. See, here was the deal -- I need a jacket taken in at the waist almost always, and nothing looks worse than a double vented jacket that fits like a box. Really it's true. Then one day I tried on a Cantarelli for Brooks Brothers double vented jacket. The waist fit perfectly and the look of the double vent started to look good. Indeed, I liked it better than the single vent because of the symetry -- you have either side overlapped by the center cloth, whereas in the single vent it is asymetrical. I then started to sort of despise the center vent because of the asymetry -- how mathematically sloppy, I thought. At this point, I just wrote off the ventless jacket because I desired that movement in the bottom of the jacket that I spoke of before. I even refused to buy a perfectly fitting D'Avenza suit that I saw at Filene's Basement for $350 because it was ventless (and it was in a fabric I absolutely loved). Now I realize that it is all just silliness. Each jacket has their own merit. None is any more inherently stylish than any of the others. They just offer different things. The ventless is obviously distinct from the vented. The double vent offers you the thrill of putting our hands in your pockets and knowing that you ass is still covered. And it gives you the satisfaction of knowing that you have a detail that most American men don't have on their suits. The single vent is more relaxed and preppy. It gives you that Americana that -- I apologize -- double vented suits just will never have. While it dumbs the suit down to "commoner" status, you can still delight in knowing that your vent hangs properly thanks to a perfectly nipped waist, compliments of your local tailor. Sew up the vent? Why. On a well-cut suit, the maker intended the suit to have a single vent. Sewing it up risks not only the cut, but is a slap in the face to the artisan (or team of artisans) that worked so hard to make it. I wear my single vented suits proudly. If you ever see me at an evening function, you will see me in double vents. But don't cast aspersions on me when I am walking home from work in my Alden cap toes and two-button, single vented, natural shouldered Oxxford suit.