My underwear choices are based on level of activity - if I’m going to the gym/playing squash then I’ll wear either briefs or tighter boxer briefs, otherwise looser boxer briefs (I don’t actually like normal boxers, I feel like I’m flying all over the place in there).
I really like underwear so whatever I’m wearing they’re interesting colours and patterns.
Let’s see…my undies are black. My clothes are almost invariably black or similar dark shades. No problem there!
I like black, it goes with everything. I have some white underwear for outfits that require it, but my complexion doesn’t lend itself to bright colours so I rarely wear anything white. Makes me look like I’ve been dead for a week.
sign
I also select it based on who I’m going to be with. If I’m going to be by myself, I have these monotit sport bras which are very comfy but, well, monotit like I said. So they don’t get worn to work or, Ogette forbid, to be around my female relatives. My male relatives keep their opinions about my boobs to themselves 
Absolutely. In fact, I do the same thing with all of my clothes. I usually like to wear my least favorites on Monday and Tuesday, then moving to my second favorites by the middle of the week. Thursday-Sunday is when I wear my favorite clothes including my favorite 2xist boxer briefs.
You first, dude.
Nope. I’m a SAHM, so as long as the panties are clean, I don’t care. I only wear a bra if I’m leaving the house, and since nursing bras are not designed for looks, it doesn’t matter which one I wear.
You guys change your underwear every day?! Whoa!
A prison warden is a real jerk, and he refuses to let the prisoners change their underwear. Finally one day he says, “Men, I have some good news and some bad news. The good news: today I’m going to let you change your underwear.”
A huge roar of applause goes up, but one prisoner, sensing a set up, yells: “Wait, what’s the bad news?”
The warden smirks: “Phil, you change with Tony. Bob, you change with Frank…”
My underpants come in white and heather gray, so it’s not much of a choice there. I use the grey only if wearing jeans or black/brown pants.
My bras come in white, beige, pink, blue, yellow and red. I do have to think about which color won’t show through the shirt I’m wearing, but that’s as complicated as it gets.
I wear these bikinis or else the hip-hugger style, under everything. In whatever color won’t show through what I’m wearing. They are super comfortable, don’t make panty lines, and they’re a micro-fiber nylon which dries really quickly–super-important if I happen to be walking and sneeze. :o
For bras, once again, whatever color doesn’t show through and is comfortable. There’s a particular brand Wal-Mart carries that fits me like a dream, and only costs $10. I couldn’t find it on their site, though.
Woot! I splurge on the Playtex brand that’s $12.97 at Wal-Mart.
First I try for one with good elastic. Then I search for ones without extra holes. Then if I have two to choose from I go for the less faded. I’d buy new ones if I had the money, but I don’t. At least I don’t have to use an orange net bag yet. 
Bob bought a hundred-dollar suit
But couldn’t afford any underwear.
Says he, “If your outside looks real good
No one will know what’s under there.”
–Shel Silverstein
(exerpt from Outside or Underneath from Light in The Attic)
all my bras are identical and all my panties are identical, all beige. I grab whatever I need and put it on. Why yes I do buy them 8 at a time … why do you ask? =)
I carefully consider my underwear options every morning. I eliminate any stained, worn-looking undies as soon as I notice them. I recently moved and discovered I had over 50 pairs of panties, so anything that did not remotely please me got tossed. I have panties I wear only with my scrubs, sleeping cotton bikinis, sexy date panties…a pair for every possible instance. Then there’s the bras.
I worked in a lingerie store years ago and the lessons stuck.
I find this choice of words unsettling for some reason.
Like most of the other women, I have some “that time of the month” pairs, which would otherwise probably be tossed out.
In general, I make some attempt to match my underware to my bra, and both to what I plan to wear that day. On occasion I’ve been known to choose my shirt because of wanting to wear my favorite underwear that day. I’m not obsessive about it - just being in the same color family and not showing through the outer clothes anywhere is good enough.
For the record, I’m currently wearing a turquoise bra that matches the turquoise and pink tank top I have on. I don’t any matching bikinis, so they’re just black.
Vat eez zees undervear you speak of?
(I pick the nicer ones first until they’re all dirty)
I don’t care how acceptable it is to others. It’s not acceptable to me. I don’t want to go about my day with it screaming, “Hey, here’s a bra!”
I also don’t wear dark bras under lighter shirts for the same reason.
Well of course not. But how about “Hey, here’s a pretty bra!”?
You guys change your underwear every day?
My word, we live in exciting times