It all depends on how much you text and email or download. The personal data plans available are either 2GB or 4GB, I'd start with the 2Gb and use it for a couple of months, if you are consistently close or go over the limit you can always up it to 4GB if need be. Given that you have a child and your new Iphone takes pictures and video, you may use up your monthly quota quickly. Texting is another killer, if you text a lot you're better served going with the unlimited plan for $20. 500 messages for $10 is another option but that has limits that, if you go over, will easily exceed the extra $10 that you'll spend for unlimited texting.