I loves me some zombie apocalypse fiction.

Slow zombies -- IGH, belt drive, heavily shielded tires
Fast zombies -- Derailleur-geared, moderately shielded tires

Dynamo-powered lights would be good, but I don't think I'd want to be out after dark in a ZA. Being able to carry supplies would probably be good, but I might want something a little more nimble/agile for quick recon work.