One of my favorite places to shop is Penzeys Spices. There's a store in Rockville, in a strip mall not far from the Metro (though, it's not close either). The shop has every spice you can imagine, including their own special mixes, like my favorite: Penzeys sandwich sprinkle, which I use for my baked sweet potato fries.
I took a trip to Penzeys on Saturday to pick up some spices and to window shop. I was out of chipotle and sandwich sprinke, so I added those to my cart, and also picked up some nutmeg and fresh bay leaves. The best thing about Penzeys is they sell their spices in small containers as well as larger sizes. I like buying small containers so that the spices stay fresh and are used in a short period instead of languishing in my kitchen for years. I have a very large bottle of cinnamon that has been around since 2002. I just can't bring myself to throw it out.
If you can't make it to Rockville, Penzeys sells their spices online.