A lot depends on how much time you have and how much you enjoy driving.
If it were me, I’d fly into San Francisco and use public transportation in the city (theirs is actually pretty decent for the US). Plus, my memories of the one time I was in SF was the sheer terror of going up and down unbelievably steep hills while my dad drove. SF is notorious for its hills. Pretty, but notorious.
Then, again, if you have the time and inclination, drive down the Pacific Coast Highway to Los Angeles. It’s a loooooooong drive. Figure all day.
Get reservations, even if it’s by calling in a few hours ahead of time while you’re on the road. I found out on one road trip that a single professional sports game can mean the entire town is booked solid. LA’s a little big for such a problem, but there might be a combination of games, conventions, political protests, and earthquakes (I kid!).
While in LA, keep the car. LA has crappy public transport, and the city is huge. It’s actually about a dozen cities all squashed together, and LA proper is only one of them. Hollywood is great for trashy site seeing. Don’t miss the La Brea tarpits, the Queen Mary, or Rodeo Drive.
Then, if you’re tight on time, fly out to Las Vegas. Everything you’ll want to do - casinos, shows, shopping - is in a relatively small area, and what isn’t easily walkable, your hotel will probably have a shuttle to. Car rental is also very easy.
Violence is much less of a problem than you might think. Don’t go off alone. If you get to a place that looks spooky or bad, leave.
Depending on the time of year you visit . . . um, actually, no matter what time of year you visit, pack layers of clothes. We Americans are notorious for refrigerating our buildings during the summer and turning them into convection ovens during winter. LA and Las Vegas during the summer are hot beyond what any sane Briton should be able to imagine. Temps easily in the upper 30s and lower 40s (Celsius). You’ll start to cope, and then you’ll walk into a store or hotel where it’s in the 20s. So, wear normal summer clothes and bring sweaters. Since Las Vegas is in the desert, it will get chilly at night. That’s American chilly. I have no idea what that will mean to you.
Some of the things you’ll notice:
- tax is not included in the sales price. Yes, this is stupid.
- tipping is expected. This is also stupid.
- Americans tend to be very friendly, very talkative, and very open. Appallingly so, I understand.
- everyone will love your accent.