It is currently ridiculous to consider Pluto a planet when it is smaller than six moons. I think it makes sense to redefine the word "planet" entirely. It shouldn't matter what it orbits, just how big it is. I've suggested this a number of time over the years. Any body at least 2000 km in diameter could be considered a planet. Any smaller bodies would be planetoids (or asteroids, comets, etc). This would also exclude of course stars, black holes, quasars, etc.

In our Solar System therefore Ganymede, Callisto, Io, Europa, and Titan, Triton and Luna(!) would join the ranks of planets. Pluto would be a planet but Charon would not. Sedna would just barely make it!