hey I'd like to add my thoughts here. Wifi is ridiculously easy to find on the road if you are traveling through the states.

mcdonalds (most mcdonalds in the US have free wifi, the only one I found without wifi was somewhere up in northern Maine). This excludes the McDonalds that are in Wal Marts. I found to my annoyance on the road that they never have wifi!

subway have wifi in most places

panera bread, they all have wifi. I"m not sure about starbucks but I'm guessing they do too

staples have wifi. i don't know for sure about other places like best buy, circuit city (does it still exisst or did they go bankrupt??) but I'm assuming they will as well

every big name truck stops have wifi that you can buy per hour if you are really desperate

pizza hut has wifi in a lot of places, but the one I tried in Moab, Utah I couldn't get the connection to work!

TONS of motels and hotels have wifi that is on an unsecured network (you dont need any code to punch in) but then tons of them you do need some password so that won't work all the time... usually smaller motels are the ones with unsecured networks but this is good because if you are in a secluded area you are most likely going to find a small motel rather than a big chain hotel

another wifi tip... just in case you are in this scenario... lots of college libraries have a computer or two reserved as a guest account you can ask at the front desk. Although this rarely happens with actual city/county libraries tho...

pretty much if you are in a big city in the US, wifi takes 0 effort. There are even many park and recreational outdoor areas that offer free wifi. In Halifax I was surprised to find the whole harbor area has great wifi connection all through. If you are in little towns, as long as its big enough to have a motel or two and a mcdonalds you will probably find wifi. Where you will be stuck is in the middle of long stretches between small towns, and of course while you are driving. But one thing that always works, I mean if you desperately need to find something online is call someone back home and ask them to look it up.

Just some suggestions in case you decide against paying the extra on your cell phone! But honestly I don't think you'll find it a huge problem... especially with McDonalds having wifi now days, there are mcdonalds everywhere and its just really simple to find.