Get the wifi iPad and save your $$$ from AT&T. Go out and buy the Clear iSpot for $100 and then you have unlimited data for $25/month on 4G speeds (avg. 6mbps down, 1.5mbps up) there is a 1GB upload cap, but what are you going to upload from your iPad?
The only drawback is you have to be in a Clear 4G area but they are adding new locations monthly and most big cities and some small already have it. I'm currently in Waco, TX (halfway between Dallas & Austin) and I have Clear 4G everywhere in Waco. I love it.