New to driving in America. Phoenix to Vegas and back

Hi there. I'm looking for some good advice. I'm a British guy and a major travel addict. So when my girlfriend's sister got a place in a Phoenix University I thought we simply had to go over and spend a couple of weeks. So now we've booked the flights to Phoenix and 3 nights in Vegas next January. But there seems to be rather a lot to see on the way. I'm not quite sure where to start! Also it seems my girlfriend's family might be there at the same time. Her parents are both a bit afraid of driving on the right hand side of the road, so it seems we will need a car that can handle 6 people plus luggage. So my queries are (apologies if this is a bit long-winded).
1. What we should be aiming to see and what is a good order to see it in between Phoenix and Vegas.
2. How to strike a balance between - my girlfriends parents with a very very limited sense of adventure (the father is dominant with a host of fears (eg heights) and and an awkward temprament but a good heart, and her mother quite timid), my girlfriend and her sister who could be persuaded to do/see most reasonable things, another 13 yr-old sister, and my own need for a bit of adventure. Thinking about somewhere like the Grand Canyon here - can we drive away from the tour buses a bit without anyone in the car feeling we have gone too far?
3. What type of vehicle do we need to reasonably see the parts of Arizona which must be seen and what daily vehicle maintainance is necessary in this environment? eg will a standard family vehicle be suitable or do we need to go a bit more up the scale?
4. Should we be looking to have accomodation booked at all stages of the journey or can we expect to roll up to a motel in most places and secure accomodation?
5. If you were planning an 8 or 9 day route inc 3 nights in Vegas, what would your rough route be? (again taking into account that for the in-laws, they have never done anything remotely similar to this before)
Sorry about the vagueness. I have just started thinking about this and am not a great planner - I usually just turn up with a backpack and take it from there. Any help will be much appreciated.

Day 1 (first on the road): Drive to Jerome, Sedona and Oak Creek Canyon (Arizona) for sightseeing, shopping, etc. Stay the night in Flagstaff.

Day 2: Drive to Grand Canyon; take West Rim drive (open to vehicles at your time of year), and East Rim drive. See the IMAX film about the Canyon in Tusayan. Alternatively, spend some time and an overnight at Grand Canyon Village, and then leave via the east rim drive and Desert View the morning of the third day. You'll receive information about what's going on in the park as you arrive, and you can use that to plan your activities during your stay. Don't rule out the ranger-led activities at either of these two Natl Parks (GC or Zion). They are often the highlight of a visit.

Day 3: Leave Grand Canyon (east on SR64) and drive to Wupatki National Monument (SR64 to US89 and south to the site). Wupatki is a collection of Anasazi (?) ruins (abandoned about 800 years ago) where there are some very interesting things to see. Continue north to Lake Powell and Glen Canyon Dam. Spend night at Page, AZ, or go on to Zion National Park. Another possibility is a lake cruise on Lake Powell, to the Rainbow Natural Bridge. Water levels are low now after drought of about 9 years, but it is still worth a look. The cruise takes at least a half day.

Day 4: Spend the day at Zion National Park. Overnight outside the park in St George.

Day 5: Drive to Las Vegas.
Day 6: Las Vegas
Day 7: Las Vegas

Day 8: Drive from Las Vegas to Phoenix (5-6 hours).

Day 9: Relax in Phoenix! Call Bob to take you around to (1) a genuine English pub, or (2) barbecue. I recommend the barbecue, as you won't find anything like it in Old Blighty! :)

All you'll probably need is a standard 4-door sedan (a Ford Taurus, for example), seats 6 and has a large trunk. Or you might request a mini-van, although the premium will be higher. Nothing special in the way of maintenance is required to drive here -- especially with a rental car as they will all be newer vehicles with no common mechanical problems -- millions of us live here in the southwest year round, and other than taking a few precautions (carrying drinking water for emergencies, for example), we don't give it a second thought.

You won't need reservations at the time of year you are coming -- even at the Grand Canyon, probably, although it would not hurt to make THOSE ahead of time. I recommend the El Tovar if you can splurge a bit on accomodations, and Maswik Lodge if you prefer to be more economical. Both are Grand Canyon National Park Lodges, and are managed by a company called Xanterra (you can find them on the WWW).

You will need to bring warm clothing -- although Phoenix and Las Vegas have temperate climates with frequent 7C temps at that time of year -- you will be traversing some higher elevations along the way in between, (Grand Canyon is 5,000 to 8,000 feet, for example), where the temps can be wintery, and snow and rain common. In Arizona particularly, we can wake up on a winter day, go for a swim, then ski at 10,000 feet after a short 2.5 hour drive! It's magic!

If this creates more questions, post again and we'll give it a shot! Bob