Depends on the market right? Per the fine print on award upgrades:
Unlimited Complimentary Upgrades are subject to availability, may not be available on all flights or in all markets, and are not valid for travel to/from Hawaii, Transatlantic and Transpacific destinations. Complimentary Upgrades are not available on flights to/from South American cities that are serviced with our BusinessElite® product (i.e., Buenos Aires, Argentina; Rio de Janeiro and Sao Paulo, Brazil; Santiago, Chile; Lima, Peru; Caracas, Venezuela). For travel booked using a SkyMiles Companion Certificate, neither the paid primary passenger nor the companion passenger will be eligible for complimentary upgrades. We limit the seats available for use with complimentary upgrades and may not make seats available on all flights. Upgrade on Award or Pay with Miles Tickets are not eligible for complimentary Companion Upgrades