If what you're after is game history, I have to think that FFIV, FFVI, and FFVII are the best choices, since they are the ones considered the most formative and/or groundbreaking.

Although it turns out that platforms may be an issue in this particular case, I'm coming around to FFIV as a good starting point in general, since it is, as you say, there's less to juggle and the DS port might be more palatable to the modern gamer than the games that only exist in older versions.