I stayed in Carlsbad, about halfway between SD and LA this past weekend. Drove all over the place because of stuff to do in both cities.
San Diego weather is great. I went downtown to check out a baseball card shop and there were crazy homeless people everywhere, so it's not immune to that problem.
I found that the 5, 405, and 10 were totally fine during off-hours. I think the traffic being bad all the time thing is overblown. But yeah, it's gridlock during rush hour times.
The good thing if the 5 is packed is taking the Pacific Coast Highway, if you don't have that far to go. It's scenic as hell. Slow, lots of red lights, etc, but pretty (except for Long Beach).
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I think I saw more Asian ladies than I previously had in my whole life. My friend brought a bunch of masks because the hotel notice seemed obsessed with them, but we didn't have to wear them. I think most of the notices and signs were out of date or people just didn't care anymore.
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My friend's cousin is the head of photography or something at the Sony Pictures lot, so we got a nice, informal tour around there. Saw all kinds of artifacts from movies and shows, and among all the stage buildings, etc. The last one was the Jeopardy one, which was cool. They put an Alex Trebek plaque on it and named the stage after him.