A while back, I made a couple of charts comparing planet sizes and distances, and highly recommended a poster by Emily Lakdawalla. I actually made a few more charts last year that I just never got around to posting. Here they are—enjoy.
Largest Solar System bodies to scale (with Saturn shown without its rings for proper comparison of just the planets):
Select solid planets and moons of the Solar System to scale:
Planets, moons and select asteroids of the inner Solar System to scale:
And finally, here's one that illustrates my planet size classification system, using median values for each size class: