Great post, Scott. I wouldn't have even felt the need to add to it, if you didn't specifically ask for professional readers to reply.
I think first-time screenwriters tend to use more licensed music in their scripts than is necessary. When it comes to using the actual song in a script, I tend to say "Don't do it. And if you must, only do it once."
And here's the other catch - you shouldn't include the songs frivalously. Don't toss in a Dylan song just because you like Dylan or you've been dying to use it in a montage. However, I'd also say you don't want to have SUCH a specific use of the song that if the rights holder says no, you're screwed. What if the song you want is key to your entire movie, but costs as much as your entire music budget?
And never, ever, EVER give editing directions, like trying to sync up certain visuals in the script with specific creschendos in the music.
Yeah, there's probably an execption or two someone can toss out there. I don't think that citing those would be productive because 99% of the time they're attached to Tarantino and Crowe scripts - which is irrelevant for most of your (unrepped) readers.
I talk about this a little more in my post
here.Short answer, I'm a big proponent of "a song like ____ plays." As far as characters singing popular songs, that's probably less likely to raise a concern, but again, do this
sparingly