My favorite longies pattern that I've come up with so far. Behold, army/harem pants. I guess these are army pants, since he's a boy and the pants look kind of camouflaged.
I made them super roomy in the butt and leg length, but decreased stitches and used ribbing to keep the legs from dragging on the floor when he walks. When he's standing up the fold on the legs just barely misses touching the floor.
And apparently I have taught him my dependence on yarn. He can't get to sleep without it. ;^)