An iPhone is an iPhone ... there's no shame in any of the iPhones imo 
Whether you sign a contract now or later, you'll have to keep it for 2 years (contract).
In fact, just thinking about it, my 3GS is almost 2 years old and its as good as ever. The iPhone 3G still looks like an awesome phone these days too, and thats 3 years old.
OP, instead of getting an iPod Nano 8GB + iPhone 16GB, I would just get a 32GB iPhone.
Whether you sign a contract now or later, you'll have to keep it for 2 years (contract).
In fact, just thinking about it, my 3GS is almost 2 years old and its as good as ever. The iPhone 3G still looks like an awesome phone these days too, and thats 3 years old.
OP, instead of getting an iPod Nano 8GB + iPhone 16GB, I would just get a 32GB iPhone.