Not for LA but I've been considering making a trip out that way from my usual stomping grounds, and Angeles Crest is definitely on my list!! From what I've heard, it's an incredible ride with amazing views, a proper mountain road with a lot of twists and turns. I was told I got to be on my game, but it's not overly difficult for a rider with some experience. You're right to expect that a portion of it being closed though, so you'll want to check Caltrans before you head out!
Another one I'm looking at is the Mulholland Highway, especially the section known as "The Snake." It's another famous biker spot with some really tight turns. Also Glendora Mountain Road to Mt. Baldy, which has some fantastic canyon views and is a bit of a local favorite!!
I still don't have a solid date set to do this, so I'm keen to get updates from you! Enjoy and ride safe!