I like Roam Mobility. They have daily plans right up to snowbird monthly plans, with and without data. You can pick and pay for any length and as long as you buy a plan (any plan including a 1 day plan) once a year it will never expire. Their rates are quite good compared to most options and data is very generous with unlimited North America talk and text and even allow tethering.
They are LTE on the Tmobile network. For some older phones this can be a problem for getting good data speeds, particularly older iPhones, but most quad band or pentaband phones should be fine.
