Great circle
In my experience, you can either use gcmap.com to get the great circle distance in miles between the airports, which will usually be with av few 10's of miles of the PQM awarded (assuming 100%), or look on the operating airline website for the mileage of your trip in their program, and then adjust for the earning rate as survived in the UA program.
Sometimes determining the booking class of the operating airline is very difficult. But you should try to access the reservation on the web sure if the operating airline, and often the booking class will appear there.