Driving from Phoenix to LA
 

I would be driving from Phoenix to LA with kids and want to cover GC,Hoover, Lasvegas on the route. What is best route to take? Is there anything that I can add along this route?

Since you are already extending the trip by doing such a large detour (375 mi. vs 710 mi. according to Google map), why not add Death Valley depending on the season?

On your way back to Phoenix stop at Painted Rock outside Gila Bend - I love this place. A huge pile of black rocks covered with Hohokam petroglyph:

http://www.petroglyphs.us/photograph...la_bend_GB.htm

I would head north and see Sedona first,then The Grand Canyon and on to Vegas via the spectacular hiway over The Hoover Dam.

s logandog says above, do go via Sedona. Quickes is I-17 to SR 179 into Sedona and then 89A though the veru scenic Oak Creek Canyon to Flagstaff and then I-40 to Williams 65/180 to the GCNP. As you make your way to Kingman and then to the Dam and LV, you could take Old Route 66 via Peach Springs and Hackberry for something different.
At Hoover Dam be sure to check out the new bridge across the Colorado River. Great views of the dam and an engineering marvel of its own.

all reasonable suggestions -- however, what is doable/advisable really depends on how many days you have for the whole trip, and if you are returning to Phoenix or is LA the end of the road??

And what month?