I think that concentrating on the body is the wrong way round. Lenses are more timeless - a good lens selection will outlive several bodies the way things change with DSLRs.
Think about the sorts of picture you want to take - try to get a sense of how the manufacturers ranges mesh with your needs (vague example - I've never managed to mesh with Nikon's lens range, finding what's good is too expensive, and what isn't seems compromised). Also - aperture specs are just as important as focal length, maybe more indicative of quality.
And as people said, see how you react to the physical feel of the product.