I'm using Maxxis ReFuse clinchers, and on the other wheelset, Continental Sprinter Gatorskin tubulars.
The numbers in computer manuals for tire circumference are only average values. The actual circumferences can vary quite a bit between manufacturers and models of tires. The best way to get a number is to get on your bike roll the bike so that the wheel which is used for speed distance measurement does a few revolutions. Measure the distance, in mm, the tire covered doing those revolutions and divide that number by the number of revolutions the tire did. The more revolutions you do, the more certain your measurement gets. You should do this roll out procedure with the tires inflated to the pressures you normally use.
Regarding tires, the desert, here, is a hostile environment for tires, but the ReFuse tires have held up great, getting only one flat in about 1000 miles.