5'11" and a 30" inseam (pant size)--pretty short-legged. I use 172.5mm on a road bike, 175 on MTB or TT bike (though I don't ride any TT bikes any longer). I'm one of those people that can tell the difference in crank sizes. When I used to race, 172.5 cranks seemed to me a good compromise between shorter, 170mm cranks (good for sprints/crits), and 175mm (good for road races/hilly rides). The added leverage of 175's is good for time trials and mountain biking where spinning/sprinting is not important. 172.5mm is what I got used to, and now I always try to find 172.5s if at all possible. I'll use 170s if it's a rare model or if that's what came on a bike (as is usually the case) but it's not my preference.
P.s. By the way, if anyone wants to trade 172.5mm Campagnolo cranks for 170s (NR or SR) or 175s (C-record, etched), I'm all ears.