It's not really about how big your legs are. IIt's more about how proportionate they are to your waist and the rest of the measurements. Which is why stuff with elastane is awesome. Those Uniqlo jeggings would fit anyone they're so Damn stretchy, but they also don't look very good.
I've posted my wheels before, I'm not out of this world huge, but still can't find a denim that meets my denimbro needs and still fits me well.