try expatsinsaudiarabia.com its a similar yahoo group and you would find useful members and information.

You would for similar salary easily save more in KSA as compared to Qatar. however thats only one part of it all.
The living conditions are extremely different as compared to Qatar - the segregation of sexes is enforced strictly and restaurants, etc will have separate entrances/enclosures for single men and families.
if you are going to be living in KSA with your family, then it wouldnt matter much, your wife would need to wear an abaya.
Trust this helps.