re: the car....on the strip, your best bet is probably to walk or cab or use some other method of transport; you just won't get around very quickly using your car on the strip.
For food: You might think of Koto, a sushi/japanese place on Eastern Ave. in Henderson; excellent food, 24.99 all you can eat for adults, and less for kids. I would call for a reservation as they can get busy on the weekends.
You might also consider Burger Bar in the Mandalay Place shops; it's a shopping mall between the Mandalay Bay and the Luxor, with upscale burgers. There is also a reasonably good tapas restaurant, Cafe Ba Ba Reeba, at the Fashion Show Mall across from the Wynn.
I second the recommendation of the Secret Garden; it's fun to watch the dolphins, and there is a new dolphin baby just born last week, so that's pretty cool, and the garden area with the other animals is shaded and pleasant. It's a bit of cash, but a nice break.