In the US, Yosemite has some amazing spots. Hike to the top of Nevada Falls and hang your feet over the edge into a 500 feet of space.
In thinking about this question, it never occured to me to pick something like Yosemite, but it is an awesome place. I remember I would go up there with the Scouts every MLK Jr. day and it was just really really fun every year. Also did the hike up to upper Yosemite falls, but never did the Half Dome walk.
Another place I love is a family camp I go to every year next to Sequoia and Kings Canyon national parks. It's a private lake, and just the environment is great, especially watching the sun come up over the trees. Another place, which I regret not going to as much as I should, is way northern California, such as Shasta, Eureka, Clear Lake, that area. I drove by there on 101 once and hopefully one day I can go back.