I used to work at radioshack too and the resources there suck. Activation will take longer than usual and they can mess up your account/credit. I hated activating phones cause it was a hassle since we were not connected directly with carriers.
I bought my 3Gs from ATT store and my girlfriends at Apple Store. Mine began freezing within the first 15 days. Went to ATT and they gave me so much trouble when trying to exchange it. They ended up not wanting to exchange it for me and said they don't take returns on iPhones, when it says the customer has a 30 day (BY LAW) return policy. SO then i went to apple store, even though i bought it from ATT, they quickly opened up a new one and gave me a brand new one, no questions asked (just their standard serial number checks). Went to get 3 more iphones for family plan at Apple, fast easy and great service. Point is ATT = no good and Apple = better.
Now for Radioshack. Brother-in-Law goes and his credit gets run twice by child who works at Radioshack and signs him up to expensive plan. So they have to call their 3rd party service provider and the manager there and employee make a big mess of his ATT account and turns out the phone they had was from a customer return, not even brand new. He ends up just getting bad credit after 4 hrs in the stuffy dusty shack. We go to apple next week, now he has to put deposit cause his credit was messed up but guess what? thats right apple waived it as they saw the mistake and he gets a brand new phone.

Radioshack = worse place to get any phone Apple = smart well trained employees
I just talked about these cases closest to me but I'll tell you those Radioshack employees are the worst to buy any cellphone from. you take a risk with your credit, used phone possibly, long activations, and bad locale. Radioshack is closest to me, then ATT, then Apple, then Best Buy and Walmart. I would take the long trip to apple before i try the first two stores. And if your other options are real far away i would recommend just ordering it on apple's website direct. Shipping is free and you know what plan youre adding. I've heard good stuff about BestBuy and dont have a clue how Walmart goes, just know RADIOSHACK IS THE WORSE, unless of course they get it right and phone works without a flaw the first 30days.