Being in Arizona, the concealment clothing has to be thought out ahead of time most of the year. November-February is not a problem, but the rest of the year...yeah, I know...It's a "dry heat."
I had a Milt Sparks Summer Special for my Sig P220 (sold it...yeah, I know, big mistake to sell it...I'll never to
that again!). The big Sig and the Summer Special worked out quite nice...very nice indeed. About the 10-12 hour mark I'd start getting tired of the holster and noticing it more, but it was so much better than other designs I tried...like those soft-suede $15 IWB holsters.
My current holster is an
Aker with a Glock 19. It fits well and I'm quite happy with it. I can tuck my shirt in with it, but still, the whole thing takes up a little room. Buying pants an extra inch or two in the waistband makes a huge difference. Putting a Leatherman-type tool exposed on the belt just ahead of the gun seems to cover up the bulge quite well.