I think the way you approach an Apple store employee or an AT&T employee will very much effect how they treat you. If you are polite and engage in a conversation that allows them to feel good about helping you they most likely will ignore rules that are not heavily enforced.
Today for the first time I was touching and actually used an iPhone 4

(made a phone call to mom). My purpose for visiting the store was to open a new AT&T account with and old iPhone purchased on eBay. During my visit I heard some interesting comments as I talked to the AT&T employees. People I have never met before today.
First, if they like you they will sell an iPhone 4 (full price) with no strings attached. Even to non AT&T customers. Remember this is an AT&T store not an Apple store.
Next and I did not know this, but AT&T store policy for
NEW AT&T customers is to require a two year contract on
ANY iPhone activated in the store. It could be a 1st generation iPhone or an unlocked iPhone 4 purchased from another country. If you do not cancel the contract within the first thirty days you are subject to ETF just as if you bought a subsidized phone. All other previously owned phones could be set up contract free (month to month). I was told this was the result of an agreement Apple made with AT&T. Once again if they like you they will back date your contract so it expires a few days after you agreed to the two year commitment.
I am no one special (wearing blue jeans and a t-shirt) but I did enjoy talking to these people, as a result they appeared willing to bend over backwards to make me happy. Although I did not ask I suspect they would have even removed the activation fee from my new account simply to please me the customer. After I complete my trial use of the 2G phone in my area and if it works satisfactorily I will definitely go back to this store and upgrade to the iPhone 4 with a 2 year agreement. Simply because of the kind treatment I received.
I really believe caring, calm, and respectful conversations with sales people will always be a benefit to the customer. Walking in a store and bluntly saying I WANT THIS or I WAS TOLD THAT in a demanding tone will turn off many sales people and result in them following all the rules.