I've found that maternity shirts are fantastic: a lot of them these days do not look like maternity tops (garbage bags), and they tend to run longer than most regular shirts. So I never have a problem with shirts riding up to show my holster belt clip. You buy in your size, so there's no bumping up to a size large if you're a medium. You get the better tailored fit in your upper half that way. Old Navy makes great tops for this.
Vests are still popular, and I will wear sporty, fleecy, or furry versions, whatever looks reasonably fashionable while doing a good job concealing.
Jeans are a size bigger to fit IWB.