Hi All We are planning a trip around N. America and would like to use our ipad with a data plan. We don't have a cellular plan of any kind now and are not very knowledgable about our options. We would like to avoid a contract and pay as we go. If we went with an American provider like Verizon, is coverage included across america? Does roaming apply? I assume we'll need a SIM card, but we don't want our device locked. Any advice or shared experience is greatly appreciated!