For more about giant trees in California, read The Wild Trees by Richard Preston. It's a fascinating story of redwood tree researchers, and reads almost like a novel.
My experience of the redwoods (the coastal redwoods in Humboldt county) is that they are SOOOO tall in the tallest groves that "tallest tree" is just incomprehensible. From the ground, the treetops are lost in the mist and fog. From 350' away, you can't really see which one is five feet taller than the other. So unless named trees are marked somehow, they're just... awe-inspiring giant trees.
I'm actually headed there late this summer. Going to try and do a big loop from the White Mountains to see some old Bristlecone Pines (no I do not know where Methuselah is), up to Redwood National Park to see Hyperion for the finale.
Redwood National Park is amazing - one of the best parks IMHO. Walking along these trees is a humbling experience. Jedediah Smith area is highly recommended
Its location is kept a secret, but it's rumored that if you know the right dendrologist, they might take you on a hike to it....
[1]: https://en.wikipedia.org/wiki/Hyperion_(tree)