Since Burt's asked about other forms of speech, and you've responded, I want to discuss the other forms that the two of you brought up:
Political: Obviously one of the most important forms of speech out there, and there should be a sky high bar to clear to suppress it. This is true even if it bleeds into other controversial parts of speech, like hate speech or campaign finance.
Symbolic: Not entirely sure what you're getting at here, and how this is different from speech in general.
Commercial: I think the first prong of
Central Hudson is fine enough: governments should have the power to lightly regulate it if it's false or misleading. However, it should be held to the same strict scrutiny standards as most other forms of speech, and that's where the other prongs veer off course.
Compelled: The freedom to speak doesn't make sense if the freedom not to speak does not also exist. Compelled speech should be held to the same high standards.
Indecent/obscene: Complete and utter bullshit invented by the Supreme Court because a majority of the Justices couldn't get over puritanical and patriarchal mores that influenced them.
Miller v. California is one of the worst cases ever that's still good precedent today. I'm worried that we're due for another ridiculous freakout over pornography and the like that's going to bring this back up in the wrong way.
Libel/Slander: As I said in the SCOTUS thread earlier in this week when
Thomas revealed he wanted to overturn Sullivan, I really dislike holding so called "public figures" to a higher standard than others. The case Thomas cites was a good one for him to stealthily make his argument: the idea that one of Bill Cosby's victims somehow becomes a "limited purpose public figure" just for speaking out about what he did to her really demonstrates how illogical the "public figure" definition is. I'd prefer holding the actual malice standard to everyone. Thomas likely disagrees but at least he's being consistent. If you have to make a distinction, I'd go with building a test on whether the defamee holds more or less power than the defamer, not on how famous one of the sides are.
Campaign finance (which I mentioned already): I think
Buckley v. Valeo back in the 1970s had it right all along: little to no protection on campaign contributions, but little to no restrictions on campaign expenditures. As such, I'm the odd cat that thinks that
Citizens United was rightly decided (at least on the constitutional question), but
McCutcheon was wrongly decided.
One more form of speech I'll throw out there: student speech, and the free speech rights of children and juveniles in general. They should hold the same First Amendment rights as anyone else. As a result,
Tinker v. Des Moines School District is very good precedent, while two decisions that shot holes into Tinker,
Bethel School District v. Fraser and
Morse v. Frederick are among the worst cases that are still good precedent, because again a majority of Justices lost their shit over kids talking about sex and drugs.