One of my favorite stationery and office supply stores is Essex Card Shop on Avenue A and 3d Street, just before the Avenue turns into Essex Street when you cross Houston. This is actually a fairly large old-fashioned stationery, office supply, hardware, and copy shop that's been there at least 30 years if not longer. Looking for a hard to find Rhodia address book, a small Rhodia 2010 daily planner, different sizes of Clairefontaine notebooks, colorful Quo Vadis planners? This place has everything and more.
The Moleskine selection is excellent, and they also carry Kikkerland WritersBlok and Leuctteurm journals. There are some really different Mead notebooks (the cream-colored graph paper notebook is really neat looking), and an interesting selection of Miquelrius journals and notebooks (I bought a few of each to use and review later). It's not someplace to browse if you are going cold-turkey on buying journals or pens, but if you are looking for something unique (a clear plastic portfolio, or burgundy metallic binder clips) then it is a great place to wander through and enjoy.
The far right aisle near the counter is paper heaven--notebooks, journals, and planners on one side and hundreds of artist sketchbooks, paints, and washes on the other side. The other three aisles are crammed with office supplies, hardware, painting supplies, paper plates and napkins, and pretty much everything else except the kitchen sink (which may be around somewhere). At the front counter are the pens and pencils, a very good selections to look over and find a few unique items.
The owner of the store is an elderly man from India, a very friendly, talkative sort. He emigrated to the US some 40 or so years ago, and has self-published a book about his journey.