The three Ive used most in your situation were the Kramer Confidant undershirt holster, a Smart Carry, and a Desantis ankle holster. All worked great, but what you wear over them, may need adjusted from your "normal" wear.
The Confidant works well and is comfortable over long days. While I have used it with a Colt Combat Commander in one pocket, and a double reload in its belt carrier in the other, two smaller handguns, like SIG P230's are a lot more comfortable. I would imagine a couple of 642's would be equally, if not more comfortable. I normally wear a fitted dress type shirt, and that wont work here. You need a full cut shirt if you want it to work.
The Smart Carry is one of my favorite holsters and one that many underestimate or blow off. You can carry some pretty big guns with them, but like the Confidant, your choice of clothing is important.
With pleated, loose fitting dress pants, Ive carried a SIG P239 (largest for me) or P230. With more fitted pants like my Carhartts/Dickies, my Seecamps are about all I can get away with. Like the Confidant, the smaller guns are more comfortable overall.
As much as it seems like a really bad place to carry a gun, its really not. When worn properly, it isnt at all unsafe, nor is it pointing at your Johnson. The way it conceals is phenomenal. You can actually wear a pair of shorts or sweatpants without a shirt while wearing it.
The gun is actually very easily and quickly accessed, even while sitting, although reholstering isnt, and usually requires work.
The Smart Carry is also the "cleanest" holster Ive ever used. You will find very little lint/dirt/junk in the holster or your gun, even with extended use, and in very dirty/dusty environments.
Ankle holsters are like the others, you need the right pants, and shoes actually come in here as well, or at least for me they do.
I normally wear 6"- 8" boots, and that makes things a lot more comfortable, and because of it, the holster usually rides a little higher. With dress shoes, I normally use the suspension strap. Its a little annoying, since I usually dont wear it, but it does keep the holster from slipping down, and with it riding higher, its less likely being seen when your pant leg rides up when you sit.
It goes without saying, you need pants with a generous leg. The weight of the material can also be an issue in some positions.
I know a lot of people dont like ankle holsters, but I find them to be handy, and with practice, not at all hard to access. These days, I normally carry a Glock 26 in one, but when certain dress limitations come in, a S&W 642 or SIG P230 replaces it. The 26 is as big as I go, and for me, its pushing the limits, especially with some pants.
So far, I find the Desantis Leather Ankle Rig to be the most comfortable ankle holster for all day use. Ive tried most of the others too.