In this summer my girlfriend and me will be on vacation for three weeks in the USA / California. We want to make a round trip and already booked a flight to SanFrancisco. From there we plan to rent a car and make a Trip from SanFran to LA (via Highway 1) to SanDiego to Grand Canyon and finally to Las Vegas.
I think we know about all the "common" sights - which also can be found on tripadvisor and other sites on the internet. But for us its maybe the only visit in California (and Nevada -> Las Vegas and a bit of Arizona -> Grand Canyon) in our life, because we're from Germany and the trip will not be very cheap. So my Question is if you have any tips for us of things we should do or places we should visit and are not well known. The tips should roughly fit for our tour route. So we are not looking for tips like 'drive over the golden gate bridge' or 'go to alcatraz'. ;-)
I know my question is a bit broad. I hope it is not too broad, so that the question has to be closed. I would be thankful for every tip!