Look up Sheldon Brown's site about chainline. Also, for a family cruiser, why would you need discs? It wouldn't be worth the time or money, IMO. Lastly, why get an internal gear hub when you've got a dérailleur hanger and a bike specific for gears? It'd be cheaper to get a dérailleur and shifters and you wouldn't have to worry about the chainline.
Lastly, I'd take a retro Rockhopper vs that POS Giant any day of the week.