How should I design a schematic component for a component library?
I generally want signals to flow from left to right, so I put inputs on the left of the box, and outputs on the right.  Power connections (if shown) go on top, and power (again, if shown) on the bottom edge.  The box must, of course, be tall enough to show all the pins, but only needs to be wide enought that the pin names don't overlap.  I would usually put the reference designator and part type above the part, not inside it. 

Spacing of pin/signal groups, as in your right example, can be helpful in separating functions on a part.