This Youtube video is a collection of every scene in which Darth Vader used Force Choke on someone in the two trilogies:

https://www.youtube.com/watch?v=T-NvFIK_beQ

[Wookieepedia's article on Force Choke](http://starwars.wikia.com/wiki/Force_choke) lists the same instances for Vader (it also lists some from his time before he turned to the dark side and became Vader). **In the films, Vader never lifted anyone off the ground when using Force Choke.**

That said, Dooku lifted Obi-Wan off the ground when choking him in Episode III:

[![enter image description here][1]][1]

The concept of lifting a person off the ground when choking him/her did come before the prequel trilogy. For example, some (now Legends) video games have a dark side power (sometimes called Force Grip) in which the target is lifted off the ground. For example, from [Jedi Knight II: Jedi Outcast](http://starwars.wikia.com/wiki/Star_Wars:_Jedi_Knight_II:_Jedi_Outcast):

[![enter image description here][2]][2]

This is probably where the idea originated from (and the games were probably inspired by Vader's first use of Force Choke in Episode IV, in which he also lifted the target off the ground, albeit physically).

  [1]: http://i.stack.imgur.com/pz5b4.jpg
  [2]: http://i.stack.imgur.com/TolHC.jpg