My personal favorite...
RDU-DFW: 1,062 miles
DFW-LAS: 1,055 miles

A mere 17 miles costs me 2 extra stickers... although I understand there needs to be a cutoff. What I would lobby for (AA's IT systems permitting) would be a sweep of the connections to total up the full mileage of the route for upgrade deduction purposes.

So for example, if you only got upgraded on one of the flights referenced above, 3 stickers would be deducted. But if both were upgraded, the total mileage would be calculated (2,117 miles) and the appropriate numbers of upgrades deducted (5).

One can dream...