Okay, you guys have convinced me. I went out to TJ Maxx today (figure if I’m going to do this I’ll start cheap, see how it goes, and move up from there if nobody points and laughs at me) and picked up four men’s shirts. Nice unobtrusive patterns that I’ve seen similar in women’s shirts, not too butch. I’m looking forward to my newfound freedom. 
I also wear them for their fit and classic styling. Most women’s shirts pose one or more of the following problems for me: too-short sleeves, too tight across the chest, shoulders, or under the armpits, awkward button placements (allowing for a flashing gap or two across the bust), have too deep a “V” or sit too uncertainly across the collarbones, and often cut awkwardly short at the bottom, so they don’t stay tucked in securely enough.
I have yet to encounter these problems with a men’s shirt. I’ve got about 1 1/2 dozen of them now, all gleaned dirt cheap (and in excellent condition, and sometimes even dry-cleaned) from garage sales thrown by corporate guys who are apparently loath to wear anything that’s been around for more than a year. We’re talking Arrow, Abercrombie & Fitch, and a slew of other names, for a dollar a pop (and even a little less). I also starch them prior to ironing… so I look like an organization man from the 1950’s or something. Could this possibly be so-square-it’s-cool? 
Yeah, I have a thing for word tees. That is, t-shirts with weird sayings on them. For some reason, weird word tees intended for girls are few and far between. They usually have some kind of sassid (sassy/stupid) saying on them like, “Princess” or “I love my dad’s credit card”, etc. so I usually end up getting men’s shirts.
My current faves that I wear are from Engrish.com. One says: “I hate my life. Every day I polish my REVOLVER and I shoot my HEAD. Like a rock star.”
Another says, “CRAP. What kind of world is this? It’s kind of crap!”
And the last is: “CALM DOWN MONKEY. You look happy today. A little say anything. What’s that smell?”
My ex-wife, who worked in the financial services industry, started wearing men’s small size dress shirts, and found that:
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They looked fine.
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Nobody noticed the difference
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They generally cost less to buy than dressy blouses, and best of all…
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It cost a LOT less to have them laundered.
For some reason, cleaning services charge more to launder blouses than men’s shirts. So, she not only got quality, good-looking shirts, she saved herself some money.
I’m sold.
May have to go out and get me some o’ these fine men’s shirts.
Today I wore to work a purple blouse with the label “Karen Scott Woman.” It was so plainly styled that the only way to tell it isn’t a man’s shirt is what side the buttons are on.
I also have a black shirt, purportedly a men’s shirt, whose label says “Arrow Ultra Silk,” made of a very soft, smooth fabric in an almost blouselike cut; anyone would say it’s a woman’s blouse except for which side the buttons are on. It feels more feminine when I put it on than the “Karen Scott Woman” blouse.
So I’m saying the twain has already met. There should exist plenty of creations with the buttons on either side that will meet the OP’s needs.
Love. That.
Just to add to the chorus:
I wear almost exclusively men’s shirts. I’m so accustomed to wearing them that I’m always a little surprised when I go to button one of the few women’s shirts left in my closet. I wear men’s shirts for everything from grocery shopping to meetings with the CEO, and as best I can tell, no one’s noticed. My reasons have been elucidated by others upthread: less expensive or better quality at the same price point, cheaper to launder almost everywhere (although my current dry cleaner, bless their hearts, charges only for “simple” or “complicated” shirts regardless of which side the buttons are on) , much more likely to fit, more professional-looking options available, the list goes on.
I only wish men’s pants would fit my breeder’s hips, because I’d wear them in a heartbeat. Women’s clothes are almost alwya shoddily made compared to the men’s, and so often come in ridiculous colors or cuts. I don’t understand why so many manufacturers think women want to resemble Easter eggs, or after reaching a certain size develop a sudden lust for kelly green, royal purple, rhinestones, and gigantic floral appliques.
FYI, my wife has been buying some man-style shirts, but made for women, lately. We’ve found some good ones at both Petite Sophisticate, and New York and Co. I dunno if either one of those places are options for you.