ideal itinerary/# of days

I'm in very early talks with my family about going to Xinjiang this September. Unfortunately, we will probably be limited by the nature of vacation days to anywhere between 7 and 14 days. Will this be enough time to get a rich enough experience of the area?

Should we only be able to go for 7 full days with access to a private jeep, what would be a reasonable itinerary and which places are mosts important to visit? What if it were 14 days?

My dad is also quite concerned about bathroom facilities outside of Urumqi and on the road en route to more rural areas. We've all traveled extensively in China and other countries in Asia, but are wondering how the public facilities compare to other areas of China/Asia.

Thanks in advance for any info!