Pablo Honey and (to a slightly lesser extent) The Bends may not be entirely, or at all, representative of their overall sound, but going in catalog order isn't really a bad idea. In terms of accessibility, OK Computer and In Rainbows are great starting points. King of Limbs and Amnesiac might be the last places I'd start with, but I guess it depends on what it is you gravitate more towards.
OK Computer is a classic on its own merit, but also an excellent bridge between the more brit-pop centered Bends and the comparatively esoteric Kid A/Amnesiac era.