Every part of the LA Arboretum system is excellent. We (SF Bay Area folks who go to LA yearly) have been to all of the other parts of the system but had never made it to Palos Verdes before. It may seem a bit far considering LA traffic for many folks including natives.
This is definitely a worthwhile spot. Remarkably quiet and I suspect underused. Huge swaths of gorgeous trees and plants. Some areas better cared for than others but in this period of serious budget issues for everyone, I would judge that the South Coast Botanic Garden is in better shape than many arboreta around the country (we belong to many and visit many more).
We were not able to get around the whole garden and so missed quite a few specific collections.
Plant labelling is just about non-existent and that's the only deficiency that I would note.
Plenty of free parking. There is an admission charge.
[Tho I respond to the length of visit question w/2-3 hours, in fact any length of visit is worthwhile.]
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