I I would have preferred for the car to not retract the handle right away after closing the door...
I would have thought the open/close thing would be pretty straightforward, so maybe I'm missing something:
A) If the door is locked, the handle is retracted. This needs to be always true.
B) If a stationary car's door is unlocked, its handle is extended. (For instance, if only the driver's door is unlocked, only the driver's door handle extends).
C) If a car goes from stationary to moving, the door handles are retracted when the car hits 5 mph (or some other reasonable speed). Many cars lock the doors in this situation - Model S could, too, but it doesn't have to.
D) When a moving car stops, the handles are not extended, even if the doors are not locked. Think stopping at a light or in traffic on the freeway.
E) When the car is put into Park, if the doors are unlocked the handles are extended. This means that if the doors are locked when the car is put into Park , the handles are not extended.
F) When a locked door is unlocked, its handle is extended if the car is stationary.
Unless I'm missing something, I think this covers everything. When you approach the car with the key fob and the doors unlock, the handles extend (see B). If after parking the car you walk away and the car auto-locks, the handles retract (see A). When you pull up to the curb to get out, the handles extend when the door unlocks (see E). That lets the valet open the door for you, or lets someone else open the door to join you. When you stop in traffic, the door handles do not extend so you won't get car jacked (see D).
Note that with this behavior, you should not ever need to push on the handle to make it extend. An unlocked door on a stationary car has its handle extended (see B and E).