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What IS an important question, IMO, is whether to allow moons of planets as planets themselves. Are we going to call Ceres a planet but not Ganymede just because of what kind of body they orbit? This is a tough question for me. It might be confusing to hear in the news that "Neptune has another planet." Or would it? I think calling spheroid moons as planets would help seperate them from the other heaps of rubble also called moons (which I think should be called moonlets or moonoids instead).
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I don't see why there needs to be a distinction. A man is a man, but from the point of view of his children, he is a father. A star is a star, but from the point of view of its planets, it is a sun. A planet is a planet, but from the point of view of its orbital planet, it is a moon. In short, a moon is a planet that orbits another planet.
Internal physics is a good idea; but it focuses mainly on the terrestrial worlds (and I think icy and rocky planets are both broadly terrestrial; Titan is more Earth-like than Venus is, but it is made of ice) rather than the gas giants. How it works in the substellar level is still unclear to me, as is the dividing line between star and planet.
I think the term "brown dwarf" has done a lot of damage to stellar classification. Brown dwarfs are not stars too small to fuse hydrogen; stars are brown dwarfs large enough to fuse hydrogen. The vast majority of "stellar objects" in the galaxy are brown dwarfs; they are therefore the standard, not the exception. Given this, it seems silly to make a distinction between stars and brown dwarfs. The one is simply a larger example of the other. Since we are almost certain within a few years to find a brown dwarf approaching jovian mass far away from any star, the term "jovian planet" may become obsolete, replaced by "orbital low-mass star".
That still leaves Uranus and Neptune, of course, but as we learn more about extrasolar planet physics, I think we may come to see them as super-terrestrial planets, rather than brown dwarfs.