Originally Posted by SEA_Tigger
Best shot is to choose "Cheapest Economy" and then "Upgrade elligible with miles - (Y/B or M/H)" which will return a fare booked in that class, and usually on the low end of the fare basis (as UA often has multiple H, M, B, and Y fares all over the map in price).
I have had mixed success with this approach. Last week, I was looking for B fares to Europe, but everytime I selected Upgrade with miles - Y/B, it gave me a V class fare.
A year ago, I got it to work, but the fares were approaching $2,000. I then tried Amex web site, and immediately got a $1,200 B fare, and with much better schedules. 15 minutes later, I had a confirmed upgrade to FRA, and of course on the return had to wait until I was practically in the jetway.