I have a J rtw ticket provided by an employer and want my wife to accompany me .

One option is to get an economy rtw and upgrade as many segments as I can . This will leave quite a few segments for one of us down the back.

The other is to buy a *Alliance RTW award .
The 300,000 mileage plus miles is fairly expensive and I am interested in what it comes with .The local UA agent have not found the appropriate rules as this type of award is rarely used .

I wonder specifically if

there is a mileage limit ?

are the rules the same as the paid rtw fares?