test the keyboards to see which kind you can handle. I went from 1-9, to qwerty, to virtual touchscreen, and i adjusted fine, but I also tested them first to see how it felt.
iphone fits all of the above and very well, unless you don't like the keyboard. email is sooo easy to use. syncing is just like an ipod, super easy. it does come with headphone w/mic. interent navigation is easy, calculator can be put on home page, and the app store actually has additional free calulators, scientific, graphing, accounting, etc. good for school if you forget ur calc, but u can't use ur iphone on a test... so don't forget it that day, and it does have gps, not the live turn by turn though. it is live, but you are a moving dot on a google map. still works for me though, and you don't have to pay xtra for it. there are free apps that support alot of different im services. you can sync with outlook, or google calendars, or download an app of your choosing for whatever kind of calendar you want.
the blackjack II has gps support(not sure if it costs extra), and a calculator, alarm clock, internet, supports multiple music format, but you have to drag and drop it into your phone. i still used my ipod with my windows mobile phone, because it was not easy to add music. it doesn't come with headphones, but it does have email support
the lg incite has gps, and a 3mp camera, it uses windows mobile, but it is another touch screen qwerty.
heres the att website with the smartphones, their specs, and prices, and even reviews.
http://www.wireless.att.com/cell-phone-service/cell-phones/pda-phones-smartphones.jsp
here is the iphone 3g info
http://www.wireless.att.com/cell-phone-service/cell-phones/pda-phones-smartphones.jsp
hope one of these helps.