Me and my friend are planning to visit the USA next year, to celibrate our high school graduation (we'll both be 18 years old by then). I have family living in California (San Francisco) so we plan on staying at their house. Of course we want to spend most of our time travelling, so we'll spend the occasional night in the hotel/motel.
We'd like to explore the state (of course not the entire state, but at least Los Angeles) and go as far as the Grand Canyon and Las Vegas. Seeing as we both have a EU driver's license, we thought we could just rent a car. However, recently I've heard that it is nearly impossible for anyone under the age of 21 to rent a car, so my question is: What is the best way to do the aforementioned things (in terms of transportation)?
Our main concern is the price. Another less important factor is the scenery.