I guess, theoretically, after april-1-2001, when UA reintroduces their rtw-itinerary (UA 1 or 2), one could cover the whole trip with one, single worldwide upgrade-voucher.

I am not there yet, but just got confirmed the following routing all upgraded from paid eco (StarAlliance rtw-fare) to business:

Tuesday, september-5-00 [*]UA 852 SIN - NRT 07:45 - 15:35 (3'324 miles)[*]UA 838 NRT - SFO 17:05 - 10:25 (always amazed that I will arrive before I depart ) (5'124 miles)[*]UA 152 SFO - ORD 23:35 - 05:19 (1'846 miles)
Wednesday, september-6-00 [*]UA 1748 ORD - SJU 07:40 - 13:14 (2'072 miles)

total of 12'366 flight miles, all covered with one complimentary upgrade voucher. Anyone did (or will) beat this?