I have been doing this from time to time for about 18 months. I went with AT&T and, at the time, got hooked into a $2 per day unlimited calls & texts plan, plus a $25 data plan which got me 500 MB. Now, to get any data for smartphones, you need to get hooked into a $25 or $50 monthly plan (can be non-recurring) plus the additional data. For the three days I was down there, I didn't find the value, but if I was going down for two weeks, I'd go with it.
T-Mobile has a pay-as-you-go plan that costs $3 a day with data included, but coverage is spotty depending on where you are going.
Verizon's plans are pricey ($80) for smartphone/data use.