San Jacinto Peak

I hiked up there via Marion Mountain Trail just after I turned 16. That's a western route and a hard way to get up there (very steep). You can get there from the east far more easily by taking the Palm Springs Aerial Tramway, which starts at the eastern base of the mountain in Palm Springs and goes up 8500 feet (and is also the largest rotating aerial tram in the world). You can then get a wilderness permit and hike the rest of the way to the peak (10,834 feet high). From the top of the peak, on a clear day, you can see into Arizona to the east (beyond range after range of mountains), into Mexico to the south, and to the Pacific Ocean to the west. The northern view doesn't stretch so far, because a taller peak (San Gorgonio, in the San Bernardino range) is present.

John Muir called it, "The most sublime spectacle to be found anywhere on this earth."

"Oh, you can’t help that," said the Cat: "we’re all mad here. I’m mad. You’re mad."
"How do you know I’m mad?" said Alice.
"You must be," said the Cat, "or you wouldn’t have come here.”

- Lewis Carroll, Alice in Wonderland