We are just beginning to prep for a small 'herb farm' in the Las Vegas area. Right now, the area is mulched and irrigated (netafim), so we are moving the mulch and defining rows. Any tips on planting seeds in the desert?

I'm in a much different climate, so I can't help with that, but I'm sure someone will be along who can. Meanwhile, it would be helpful to mention what specific herbs you're planning on growing.
to ATP!

You might try mixing some Soil Moist
http://www.soilmoist.com/
in with your soil before you plant. I also think I would set up an umbrella or canopy of some sort in the heat of summer. Something to provide shade in the afternoon.
Good luck with it, and let us know how it goes! My daughter grew plants on her balcony in Las Vegas, up until the week she came to visit me, and nobody watered for her and they all fried.
Her plants actually required less watering than mine do here because her nighttime temps were cool.
Welcome to ATP! There's several members on here from the Vegas area.

Hmmm, you know, Cindi, maybe they could do something of a variation on what some people here in the frozen northland do for protection from frost, except instead of insulating plastic, use shade cloth. Sort of long hoop houses covered with shade cloth. Wonder if that would help.

I use plastic lawn chairs here in Kansas. If you can find the kind with narrow slits in them, where some light gets through, then you can grow tender plants like lettuce for a few more months. Works pretty well until the wind gets too high.

For starting seeds, the biggest challenge (if you don't have a greenhouse) will be to keep them moist until they germinate. A very low frost cloth tunnel might work. A little micro-irrigation setup with timer set to mist the seedlings every few hours during the day would also speed things along.

Also, some herbs that came from the Mediterranean area really like dry air and hot sun. I do agree that in summer, something to protect the rows from the blazing heat would help a lot, but also growing types of herbs that are suited to more arid climates will be a good idea. Sages, rosemary, oregano, thyme, and lavender (which they already grow commercially up in the deserts of Mona, Utah) would be good.

If you want to grow herbs that need more moisture, (like Basil which does great here in FL) then something like a frost cloth tunnel might give a 20% or more reduction in sun intensity, and also hold in a little bit of humidity. It would also help extend your season, as you could start plants earlier in spring and hold them longer in fall.