My recommendation: full-size AT&T iPad2 with no data plan. AT&T gives you the option to get a dataplan on a month to month basis in case you need it at a future time. (I never have needed to because wi-fi is so readily available.)
I also recommend Dual XGPS150 for better GPS reception.
Then, get an iPhone in case you need internet at remote places.
Reason for my suggestion? That's what I have!
You will find that you use the iPad+iPhone for a lot more than just aviation.
