In reply to Wally:
Hmm, that's a tall order. Vegas can consume 2 weeks just in seeing all of the things to see in and around the place, though she'll probably want to have a wheel chair or mobile scooter thing due to how far away things are (even inside the casinos).
I'm not a huge fan of Vegas personally, so a couple of full days or a few nights are plenty for me since they usually involve a little shopping with the wife, some great food and drinks and a show or two. The rest of the time its either day trips or lounging by the pool.
Grand Canyon was an awesome sight. Truly worth seeing at some point in your life, pictures just don't do it justice. If I had to do our last trip to Vegas again, I'd have either gotten passes to SEMA and hung out there all the time or I'd have booked us a room at the lodge there at the Grand Canyon and just sat on the porch with a cup of coffee every morning. Wish we could have done the helicopter or boat tour as it was just that awesome. The Jeep tour we did was a lot of fun, but a little harder if you have mobility issues getting into and out of the back of a jeep.
Anyway, a trip to Grand Canyon is an all day bus ride to/from Vegas including the Dam tour and pretty reasonably priced depending on the options.
https://www.pinkjeeptourslasvegas.com/
Vegas has the huge ferris wheel observation thing, which is stupid cheap via Groupon and you can get a car with an open bar (how many can you drink in 30 minutes?) and at night the view is pretty damned cool.
http://www.vegas.com/attractions/on-the-strip/high-roller-las-vegas/
A few great car museums as well as Vegas Speedway, perhaps time your trip with a race there or perhaps one of the track excursions they have?
From Vegas to LA its about 4 hours (on a good day), so you could do a couple of days in Vegas, maybe Grand Canyon and some night time stuff before heading West to LA where you could North or South on 101 for a bit.
http://www.fodors.com/news/ultimate-road-trip-from-la-to-las-vegas-7176.html
Or you could fly if you don't have a car and pick one up in LA.
If you go North along 101 you could head to San Francisco. I'd suggest one of the hop/hop-off double decker busses for seeing San Francisco as driving there can be a pain. There's also winery tour bus trips to Napa Valley available which also hit some historic places like the Presidio, etc. Of course Alcatraz is a pretty good day trip, lots of walking for that one, but they allow wheel chairs if needed. In the fall it can be a bit cool and occasionally rainy or foggy in San Francisco, so plan accordingly.
There's the road course in Sonoma which you could hit as a stop on the way to San Francisco, check their schedule and maybe see if there's an event you could line up.
Muir woods: http://www.sftodo.com/muirwoodssanfrancisco.html
Presidio: http://www.nps.gov/prsf/index.htm
Alcatraz: http://www.nps.gov/alca/index.htm
Hop-on/off: http://www.hop-on-hop-off-bus.com/san-francisco-bus-tours
Sonoma: http://www.racesonoma.com/
http://www.karenbrown.com/Trip_Planning_Itinerary/California/San_Francisco_to_Los_Angeles_Via_the_Coast/74.php
If you go South you could hit San Diego:
http://www.sandiego.org/
My personal favorite is walking along the water front and maybe taking one of their night time boat rides around the bay and then spend a day at Balboa park and hit the museums (Air & Space, Automotive Museum, Model Railroad Museum, Science Museum, Natural History, etc.) kick back and people watch for a bit.
http://www.sandiego.org/what-to-do/tours-sightseeing/sightseeing-tours.aspx
http://www.sandiego.org/members/visitor-information-centers/balboa-park.aspx