My girlfriend and I (both 23 and Irish) are arriving in Vancouver in late September on a one year working holiday. Before we get settled into working we had hoped to travel down the west coast of America (hoping to visit San Francisco, LA, Las Vegas, Grand Canyon etc etc). We hope to spend between 2 - 3 weeks doing so and are desperate for any advice from people with a bit more experience. I have a full Irish driving lience so I would probably be looking at renting a car in order to complete the trip. Any advice on rental services, must see destinations, or anything else that might be useful for first timers planning such a trip would be greatly appreciated!

Thanks,
Phil