I recently switched to Cricket Wireless. Now owned by AT&T and using their towers, I get unlimited calling and text throughout North America, plus 5gb data for $45/mo., net price. (More data available for purchase.)
I use an $8 App called PdaNet - www.pdanet.co ('.co', not '.com'). This allows you to securely connect your laptop or tablet to the internet through your Smart Phone without a phone company tethering plan.
I have found CG wifi to be sufficient most of the time. For banking or paying bills, I connect securely through my phone.
Is this a 'gray' area of the wireless contract? Don't ask, don't tell and don't be obvious.