Originally Posted by margarita girl

Yes, if you make the booking for 2 people and the blue box is still there, that means there are at least 2 upgrade spots. Many of us use this method to determinine how many upgrade spots there are, i.e. increase the # of people by one, and repeat a number of times to determine at which point the box goes gray.

P.S. Latitude fares are fully cancellable, so there is no risk in trying to book it. Actually all fares are fully cancellable within 24 hrs of booking.