The order really doesn't matter. Star Wars is a saga that I can't see someone watching just once, it's something you experience over repeated viewings and that's how you fully understand things. The assumption that someone is going to get something by watching in a certain order can only be made if they even make that connection. Palpatine's duality role is not even needed to be known to understand his purpose in the OT, in fact, any reference to his political importance is done very offhandedly and doesn't drive the story in any way, unlike the PT.
So yeah, unless this person is only going to view to saga once, it really shouldn't matter what order things come in, well other than mixing up the OT and screwing up things storywise. They just simply aren't going tog et everything in any little order you come up with, they may be more likely to realize more from one set of viewings to the next, but this is just a silly. But I do prefer seeing the films in order of release as that's how I grew up watching them, and I would never want to take that experience away from someone completely new to the series, I think it loses some of the magic, but perhaps I'm just being far too nostalgic.
Prospero also makes a very nice point. You're missing on other things you may not even notice. The music is part of that magic and the experience is going to be vastly different than how everyone else has experienced. I just don't feel that changing that is the best way of showing off the films to someone.
