Okay. So I’m an idiot, I guess. I’ve wondered aloud in my previous post about why there is not a font that includes both polytonic Greek and Hebrew in one place. I never read the resources that I recommended in my original post about unicode well enough, because The Tyndale Tech Bulletin clearly states that Cardo has both Greek and Hebrew–it also has Coptic and apparently every character TLG lists. Duh!
So after doing a few quick tests of Cardo‘s look–English and Greek (my two primary), I think it looks great. There were actually a couple of things with Gentium (e.g., the italics ‘l’ doesn’t italicise), and I didn’t see anything weird with Cardo. It looks very Times Romanish. So unless something weird creeps up it will be my overall unicode font from here onwards.
[Update: Looks like I'll be sticking with Gentium. Cardo is a 'large font' per its website. Apparently that means that it takes up more space vertically than a normal font, so line spacing gets wacky with Cardo. It's enough that I don't want to have to fool with changing line spacing depending on which font I use--it kind of defeats the purpose universal switchability of unicode. Since I'm not doing Hebrew it's not really a problem, but it's unfortunate.]