uniform pants from Lands' End have this treatment. The twill is thick, so they did the facing out of pink oxford cloth and the pocket linings out of pink stripe oxford shirting instead of self fabric or plain white, even though I'm sure it cost them more to do. I love the idea of haberdashery details on the inside even if none of it shows from the outside. You just know it's there when you're wearing it. It's a psychological thing, mostly, but it does make for a nice flat waistband, even with button elastic in the back of it.
bias tape maker to get a nice perfect piece of binding.
Then comes my favorite part- "crack-stitching" or "stitching in the ditch". I didn't photgraph this part, but I've blogged about it in the past here. Pin your facing flat with the corners tucked in like above. Turn the garment right side out. To close the waist you will stitch in the seam crack where the body meets the waistband. You won't even see the stitches on the outside when you're through. An edge joining foot makes it easier, but it's not difficult to aim your needle right into the crack. Finally, feed your elastic through the waist through the buttonholes.