I use to live in the Mojave desert area of California so feel your pain. I tried all sorts of combinations of light weight tires with kevlar, add a liner, add a thorn tube...still got flats. Then a LBS told me about Specialized Armadillo All Condition tires, so I tried them with Specialized ultralight racing tubes as the lbs said to do; I didn't have another flat for about 15,000 miles and that flat came because I wore a Armadillo down to the cords. The Armadillos last a long time too, I managed to get about 5,000 miles a tire. The Armadillo also extends their Armadillo flat protection into the side wall making the sidewall almost impossible to damage or penetrate, but it does make the sidewall really stiff which means the ride is harsh; but I discovered I could run about 15psi less in the tires then a normal tire because of the stiff sidewalls, this lower psi soften the ride a bit.
I did try using Conti Gatorskin, and they failed to stop goatheads by themselves, add a Mr Tuffy liner and then they would work, but the Gatorskin uses a paper thin sidewalls which is subject to damage and penetration.
I've actually had goatheads penetrate a Mr Tuffy, so I wouldn't rely on those alone. Also if your riding a road bike don't bother with Slime tubes. I tried the Slime tubes and due to the fact that on a road bike your using 95psi or more as soon as a goathead punctured the tube the tire was flat. So you go to pump the tire up thinking the Slime would seal, which it does until you get between 65 and 70psi then the pressure would just blow the Slime out of the tube and the tire was flat again. Slime is great for lower pressure mtb's but not so great for road bikes.