Bingowings said:

There must be a way of altering the PT to keep all the surprises intact.

There’s a very simple way of doing that: put it after Ep5. (Or after Ep6, but I prefer it after Ep5.) I can’t image any way to edit ROTS to preserve the Anakin = Vader surprise in ESB if ROTS is seen before ESB.

TPM just isn’t a very good introduction to the Saga, partly because it just isn’t a very good film. ANH does a much better job of “grabbing” the viewer and making him care what happened a long time ago in that galaxy far, far away.

ANH is by a wide margin the best way to start the viewing experience and ROTJ the best way to end it. The best way to watch is 4-5-1-2-3-6 or 4-5-6-done, depending on whether you consider the PT to be worthwhile.

If you do want to watch the PT, it works best between Ep5 and Ep6. Anakin’s descent into darkness is more compelling if you have seen the end result of the fall but haven’t seen him break free of it. The rise of the Empire is more compelling if you have seen the power and brutality of the Empire but haven’t seen its imminent demise.