The consumer (Grocery/chain pharmacy) diapers are largely crap. The best I've come accross are the Wal*Mart Assurance and their Sam's Club equivalent (and someone tells me the WalGreens markets the same diaper under their house brand).
Oddly enough, most medical suppliers and pharmacies including WalMart or CVS can order you anything you want for store pick up. You can get into the better of the US marketed brands: Attends, Tranquility, Tena. Many of these companies have websites that will tell you if any pharmacies or med supply stores in your area stock their product if you go to their website.
My favs are Abena and Molicare. They're fairly recent to US distribution but you can still find them if you hunt.
The other option is to mail order them to be shipped to a UPS Store or the like so.
Didn't know that you could get pharmacies to order-in specific brands! This is very convenient, and figured I'd share it. If you can build up the courage, you can get "premium" diapers without needed online shopping. For the most part.
PS Excuse my terrible formatting, I don't blog often.