To answer some of the questions posted here:
1) The 767 winglet program is slowly progressing however it is only being done currently during the off peak travel times as AA
needs every available aircraft for the peak travel months. There was a suspension of the program for several months due to some technical issues that cropped up however they have since been resolved. Although the actual installation of the winglets is approximately three weeks, AA
is using this time to install new avionics in the flight deck (replacing the old CRTs with new LCD
screens and upgrading all the computers and navigation computers as well) to make them compatible with the new ATC requirements worldwide which adds a few days to the downtime. All the winglet installations are done in-house.
2) The reason that the GoGo WiFi isn't in the 757s and 767s as yet is that GoGo will be rolling out a new satellite augmented system next year which will allow Transatlantic and Transpacific internet connections. The new system is not compatible with the existing system so instead of installing the system twice AA
opted to wait with the installation until the new service is available. The first aircraft that will have it installed is the 777-300 coming late this fall. Also with the 757/767 aircraft being used predominately outside of the US mainland (the only place GoGo is currently available) it would not be good to mislead passengers into thinking they had WiFi connections for the entire flight when in reality it might of be for the first hour or so. The 767-200 aircraft all have WiFi as they are used solely on US domestic routes were GoGo is currently available.
In the meantime the 737 fleet is getting it installed as they rotate through Tulsa on longer maintenance checks (the new aircraft are getting it installed prior to entering service). Believe it or not, the Gogo system is only being used by a very small number of passengers and is not the money earner that people might expect. Still as the competition has it, so everyone is forced to have it. To recoup the installation costs and subsequent downtime on the aircraft unless the aircraft is already scheduled for a check would take a very long time just based on the current amount of users. Hence it is done in combination with other work that the aircraft require from time to time.
As fuel savings of the 767 winglet, I remember reading somewhere that it was around 5-6% of the fuel burn however there are many factors that determine the exact amount. I think it is safe to say it is probably 3-4%, which would make the installation economically viable.
TWA-Gone, but not forgotten...