If both the Wife and I are applying for jobs in Qatar and we are both successful, who decides on which one sponsors the other one, i.e. wife or me when we both come over in Aug 2012?

Is their a hard and fast rule that for best value I should go along as being sponsored by the wife who is the teacher or should I sponsor her when I begin my job working for the transport industry in Qatar?

Any ideas to best decide this would be greatly appreciated.