All regular (non-smartphones) qualify for the $15/month AT&T data plan. That gets you Internet (web and email) access via AT&T's data network. It also gets you their streaming video service and data services for that cool Google maps application you discovered on the iPhone. But you need not take any data plan with feature phones, so you'd just pay for your monthly minutes and a text message plan if you wanted one.
Certainly the iPhone is probably the easiest smartphone to learn on the planet! Easier than a BlackBerry and lots of fun. Not to mention useful things like maps, web and email. But I was trying to save you from that $30/month since you mentioned it exceeded your budget.
AT&T's feature phones with full QWERTY keyboards include: Pantech Slate Pantech Matrix Samsung Propel Quickfire
These require no data plan at all, and if you do want one, it's $15/month. None are as much fun as the iPhone though, and they don't sync easily with a computer (smartphones are better if you decide you'd like to sync with the computer).
-------------------- Lisa Gade Editor in Chief, MobileTechReview