Beyond line of sight requires a VHF to bounce off a repeater. And you need to be line of sight to a repeater (they are usually on high points, so that makes it easier). In developed area you will find lots of repeaters. There are repeaters from Corona to Banning and Crestline to Temecula, so the Inland Empire is covered pretty well. But for instance there are no repeaters in Death Valley National Park, so you better be on Telescope Peak or Dante’s View if you want to have a chance of hitting a repeater. That is not to say that you might not reach another ham in the general area. A lot of offroaders seem to run 2 meter VHF radios.
HF can bounce off the ionosphere (VHF generally goes right through it into space) and therefore can get you a lot further out. Like to other countries further out. Operating in the HF bands that will be the most useful in getting long distance require a General license. Technician is the first level of license now and General is the next level. The tests are not too bad if you are a techie, but if you are non technical they can be hard. My wife the accountant passed her test the first time after she took a "ham cram" class, but just barely. She just memorized enough to pass. She still can’t tell a resister from a capacitor. But then you really don’t need to know that to operate a radio these days. Check the band plan for what frequencies you can use, dial up a frequency, push to talk, use your call sign every 10 minutes and be polite. Most VHF radios won’t let you talk where you are not allowed to be. For the General test I had to remember a lot of college physics. It was actually fun to relearn that stuff.
It sounds like we might be covering some of the same ground on our trips. I am just coming out of the Bay Area and will end up in southeastern Utah and southwestern Colorado. Have fun and pack a cell phone.