I am soon to come into possession of my very first electronic tablet - a IPad with WiFi/3G capabilities. My decision to go with the dual option was because of reading that an unlimited data plan for it would be $30/mo through AT&T. I then (after having the order submitted) happened across some information stating that (as of June 7, 2010) the unlimited data plan would not be available to newcomers. In its place would be a 2GB plan, at $25/mo.
I don't know as to what would constitute the biggest 'bite' from that, and hope that I can get some ideas here (my internet activity, for the greater part, would be just for surfing & emailing). The dual usage models are $160 more than than the WiFi only units, and I don't want to find that I might have to shell out $50 (or more) per month, because of exceeding the 2GB limit. If that were to indeed be the likely scenario, I will send the unit back - unopened - for a singular (WiFi only) model.