The prices on current Carhardt give me pause--and some of the "ledgendary" quality has become more mythical. But, that's just my opinion.
Dickies and Duluth have filled in the gap to a goodly stretch.
The blanket-lined Carhardt gear is still pretty good, if at close to LLBean sorts of prices (and you get what you pay for).
As far as pants go, Ive come to a similar conclusion. Dickies Carpenter pants are most of what I buy anymore, and they have gone up in price as well, but are still about $20 a pair cheaper than Carhartts. Carhartts are still the way to go for bibs though.
Duluth's stuff looks to be OK, but I put it in the same boat as Carhartt as far as cost goes, and they are worse there. A number of guys I used to work with liked them, and one guy used to just "trade them in", or so he said. Apparently, their stuff is supposed to be guaranteed for life. I guess at $70 a pair, they ought to be.
No matter what you choose, if you're going to carry IWB, I would suggest buying your normal size, and dont size up. Unless youre not being honest with yourself as to your size, the gun doesnt make any real difference, and between your pants giving a little, and your body doing the same, it may feel snug when you first put things on, but a couple of minutes later, you dont know its there. There are a couple of advantages here too. One, your pants fit without the gun being there, they dont look like they are the wrong size (which they are if you size up), and when you do have the gun on, the pants help secure everything and keep things in place, and youre less apt to have to keep fiddling with it.
Im assuming here the fabric weight/thickness thing is more about pocket carry than it is IWB? Im just not seeing where it would be an issue with IWB, as you will likely have something over the gun anyway.
Im not a pocket carrier fan, and never really liked it, no matter how heavy the material is. After a while, unless youre using a hard holster, youre likely going to start to see a gun "Skoal Ring" in that pocket too, if the gun is always there.
There are also a number holsters out there that spread the "lump" out if thats a worry for you, so there are ways around things.
The other problem is probably going to be your belt, as true gun belts tend to look like gun belts, and most dress pants tend to only take narrow little belts. The narrower you go with the belt, the more like a torture device it comes, especially if there is weight on it.
If this pant thing is such an issue, then maybe a holster change is more in order. Ive used one of Kreamers "Confidant" undershirt holsters in the past, and it worked well under business attire and a full cut oxford shirt. You can wear it over a normal tee shirt, so it looks right if your collar is open, and its also more comfortable. And as Ive mentioned above, the Smart Carry, which these days, is my preferred way to go for this sort of thing. Both allow you to wear your normal clothes, without having to buy anything special, and both worked well for the need. You can be well armed, and in just a tucked in shirt and any pants you want. You also free up all your pockets for all that other important stuff you sem to have to have in them.