Depends, for commuting and riding in the UK, I'd say the normal ones are fine. If you're going to be doing lots of descending, the Ice Tech ones are better. Ice tech will need replacing more often though, and if you're going to using them on busy dirty roads it might not be worth the extra money.
Anyone had any experience with the new Shimano centre lock rotors - is it worth buying the fancier ones, or will the cheaper ones suffice?