I have brown and black for my most oft carried piece, a somewhat customized now RIA 10mm. Reason being, I want the color that blends in with my carry clothes that day i.e. if my cover shirt or jacket rides up a bit or gets windblown a little a color matching my clothing is, i think, a little less likely to be glaring out at everyone. I wear a lot of black Wranglers and Black double front, padded knees Carhart pants with black or grey T-shirts so often have a black belt and boots and gunleather at the same time. Everything just kinda blends together that way.
The only holster I have for my 329PD, as it is mostly a mountain fishing, big game hunting back up and trails gun, is plain brown. Outdoors I will be wearing brown, tan or camo a lot.
Have to say here that I find myself choosing the 329PD for carry more oft than I originally thought I would due to its wonderful light weight. Going to have to get some better sights on that bad boy soon. And a black holster.
All of my carry and outdoors wear holsters are pancake style outside the waistband and snug to the hip style.
My P3AT 380 does not have, or need, a holster