I did the high-waisted drawstrings for clinicals - plus I got them a size bigger than I needed.
With the high waist, like the poster above, I pull them alllll the way up, and then tie them at the base of my ribs with a double bow. They don't move that way! It sounds hilarious, but they really do make them that way and they really do stay put. Tying the drawstring takes a little bit of finesse, but once you get a method, you know how to get them on so they don't start drooping after you've bent and squatted and stretched and sweated all day long.
As for the size larger than necessary thing. I would really hate to be running around and squatting and then hear a "rrrrriiiiippppp"! You put a lot of stress on your legs while you work. Bending, squatting, pivoting, stretching, all this and more, all while sweaty. And it really stresses the seams of your pants. Especially if you have a little bit of extra cushioning back there like I do. I have scrubs at home that I wear, and they fit right (are a size smaller) but after a few months of use, they're starting to give at the crotch/butt seams. So... bigger scrubs go to clinicals. That's my little bit of advice!