Such a great opportunity! I encourage you to record the everyday hustle and bustle of life…you probably won't need to travel too far to find really interesting material. Try settling in somewhere for a couple of hours; once people forget you are standing around with a microphone they will return to their normal behaviors, much like nature recording.

And please consider posting your treasure trove so we can all enjoy it! Be safe -

Desert ambiences and open-air markets spring to mind. I have a friend who grew up there; let me ask her what else to go after.

Addendum: @Rob - She says,

"We went to a small city called Al-Khobar all the time to go shopping, and there's some hustle & bustle of cars, buses, people walking & talking, etc. Except for the language, though, it's not much different from other cities. That is, until prayer time. Almost all mosques have speakers that broadcast the prayer calls outside so that folks can pray wherever they are. That's pretty cool. You can't miss it because all the stores close for about 15 minutes.

My favorite place was Hofuf, which was a small village near an old fort, and it had a couple of markets, including the camel market and the folks who make pottery. The camel market is full of great sounds, as you can imagine. I'm sure there are several in the kingdom."

The call to prayer would be interesting!