You can only get the One on One service if you purchase from Apple. I think, maybe no need. The prices at Adorama these days with Apple Care are in some cases over $500 Apple list price.
The only advantage that I can see buying from an Apple store vs a quality online retailer is the instant gratification of hands-on with your new prize.
My two online purchases have been with MacMall and Adorama. Use the price guide to determine who has the best price for the desired configuration. Amazon will collect sales tax and so will any retailer who had a point of presence in your state. MacMall would have charged me sales tax but I had the Macbook delivered to my niece in a state next door. Right now it is hard to beat Adorama prices with Apple Care.