Personally I would choose the 3G model unless you have a device to hotspot internet to it. You could always move around music and movie files as you need them but you can't use the web whenever you want. I wouldn't use my iPad as much if I didn't have 3G service.
Went with the 32GB WiFi/3G b/c I'm always on the go and read many email with attachments. Don't need 3G if you are at school, at coffeeshop with free WiFi or you're able to find hotspots...(there's an app for that!) 😛