I waited in line 2+ hours on launch day for the iPhone3G. Last year I pre-ordered my 3GS and had it delivered the same day as launch at 10am by Fed Ex. My advice is stay at home, sleep in, and wake for the Fed Ex guy. Going to the store will not do anything for your troubleshooting issues, which I doubt they will have (they seemed to have learned their lesson after the 3G launch).
You wanna know how they activated my 3G on launch day?? The same way I did the next year with me 3GS, they opened it, put in my SIM card, and connected to iTunes. That easy! If it won't activate or you have a problem with your AT&T account, they won't be able to help in all likelihood.
Save yourself the time of waiting in line, because even if you pre order and go the store to pick it up, their will be lines. There will always be people who can't wait 3 hours for a fed ex truck to bring it to you, and there's a lot of them in the apple world!
nice... thats sounds good... who did u pre order it from apple.com? i think am going to do that cuz i called the att store near me and he told me no matter if am the first person there on the 15th to preorder he cant gaurentee me a phone am like ok so if am pre order #1 and u get 30 phones that day ur gonna tell me iam not gaurenteed a phone.. he said correct so i just slamed dunked on him....