Appropriate rental car for national parks

Hi,

We are planning a road trip across the US National Parks and we are still in doubt about the car we should choose. We don%26#39;t want to break down in the middle of Death Valley, so we want to make sure we have the right stuff. We first thought about renting a Ford Focus but now we aren%26#39;t that sure about our choice any longer. Do we need a more powerful engine for a two weeks trip in the middle of the summer? Other parks we plan to visit include Joshua Tree, Grand Canyon, Bryce Canyon, Yosemite and Zion. Should we get an SUV (higher suspension)? Or maybe a car with extra hp?