Prior to the Internet, I bought all of my Nikon film bodies (refurbished), Nikkor lenses (refurbished), and all of my film and accessories from Bel Air Camera in Westwood (Los Angeles). Bel Air was a pleasant place to shop with a nice, friendly sales staff, and lots of pretty UCLA college girls walking around.
After about 1995, I discovered B+H, and since then, 99% of my photo/video purchases have been made online at B+H PhotoVideo. They're extremely reputable and have thousands of items in-stock. I've only made one purchase at Adorama, when they had a killer price on an expensive refurbished Nikkor lens (although, Adorama's refurb prices usually tend to be on the high side). I've also purchased quite a bit of Nikon gear from Ebay resellers, and have gotten some really excellent deals.
New accessories, I often buy at Samy's Camera on Fairfax in Los Angeles, for convenience's sake. They're also one of the few ThinkTank retail dealers, and have many of their excellent products in-stock to try out. I've also purchased several used and refurbished lenses from Samy's. I like supporting local dealers, and both Bel Air and Samy's will discount my purchases (when asked), and often either meet or even beat B+H's prices. Both retailers also hold "no sales tax" sales quite frequently.