Unless I'm mistaken, Tech Package adds the following. Personally I would not buy a Model S without the tech package. Especially the Power Lift Gate is a big must for us and so are cornering fog lights. They are really useful at night for illuminating curbs and the street you are turning into.
Autopilot convenience features available through software updates (For cars built after ~ October 2014)
LED cornering lights, and fog lamps
Automatic keyless entry
Lighted door handles
Power liftgate
Electrochromatic mirrors
Power folding, heated side mirrors with memory
GPS enabled homelink