Absolute fabulous; try to avoid going during peak times in the summer and on weekends. Some of the best hikes my wife and I took there were weekdays in the fall/spring.
Don't be decieved that you can drive around the mountain in a couple of hours; you'll want to stop and see stuff.
Also consider the north side of the park; nowhere near as busy, and you get a much better sensation of being truly in the "wilderness."
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