Update my 4gb 1st gen iPhone with fw 3.0 sell it for a good price, keep my 3g 16gb as a back up, and buy the new iPhone (might not be able to get it for the sub. Price but oh well)
Other-
I will probably keep my 16 GB 3G, Because I am VERY satisfied with it and unless Apple releases something I "NEED" on the new iPhone (which I doubt because I don't NEED anything more) I may just get a new iPhone and cancel my current contract. But I doubt I will get a new iPhone.
Increased battery life?
Add it as a new line on current family plan, wait 31 days cancel line pay $175 ETF
Sale 'old' 3g that is JB/Unlocked to recoup some $$ and continue with life.