The AirBnB i booked for my holiday in California, doesn't have wifi. Do you have any idea what devices are available in the States for mobile wifi? Like dongles, mobile hotspots etc.
all major carriers in the US have mobile hotspots for sale. Like AT&T, Verizon,...
I think your best bet would be t-mobile. www.t-mobile.com
They have pretty good rates, but I havent found any WiFi hotspot on their site. But as alternative you could get a phone which has the capability of doing its own wifi hotspot.
But make sure it is included in your plan. I know on verizon you have to pay extra for that feature. Even tho you have mobile internet on your phone, without the extra fee you cant use it as hotspot.
Also check the websites of the carriers if they have coverage in your are of you airbnb home.
It also depends, how often and how much you want to use the internet. If its only for a couple of hours in the evening, you could go to Starbucks, McDonalds or a lot of other places, which offer free WiFi. Also check your Credit Card, some of them offer a free Boingo subscription, which gives you also free wifi in a lot of places around the globe. But check on www.boingo.com if any spot is close by.