SML is great, but I always suggest OCaml. Still my favourite language that I never get to write these days!
For practical programming I'd probably agree, but if the point is to learn a non-Algol way of thinking then I think SML is a better way to go; OCaml makes it easier to write imperative-style code, for better and for worse.
Nah, go with an ML-family language. Maybe even Standard ML, because it will nudge you away from writing "C in ML" and encourage you to pick up the idiomatic way of doing things. (Laurence Paulson's book has an online version available for free on his homepage).