I am not with AT&T and I dont know much about their plans. ..
In my home there are android ,windows and Blackberry phones. I believe any of those will charge you for data plan and you said you are not really wanting to pay for that service. But If what you need is battery life? Blackberry is the way to go. After fully charged, they last a couple of days or more depending on the usage. I use mine a lot and it last 2 days without recharging....