When tethering a laptop to an iPhone for mobility, is there a benefit to using bluetooth over wi-fi? Or USB?
There is no benefit to using Bluetooth over Wi-Fi or USB. However, you will have to set it to "Internet Tethering" to enable a quick tethering process. Get detailed information on http://techtips.salon.com/tether-laptop-iphone-2273.html.
I like using a USB to avoid losing data because Bluetooth battery died ect.