Ost Cafe in the East Village should be in your rotation. The floor to ceiling windows give a nice view of Avenue A, and they open them in the warm months which is great for people watching. Will be stopping by there today to do some work before going to an art show in Brooklyn this evening.
The baristas are awesomely nice, and they don't mind if you sit for long periods of time. Try their Chai Lattes and almond croissants. You can get hours/directions here.
If You’re New To New York: For those who have lived in a major US city, are thinking about moving here, but think it’s too expensive: It’s a bit more expensive for things like groceries, laundry, shelter. But this won't break your bank (especially since you make a hell of a lot more money here). AND we don't have car payments/gas/insurance to worry about, so that helps. But it’s RIDICULOUSLY expensive to party here. And New Yorkers eat out A LOT because our kitchens are so small. It comes down to opportunity: What are you willing to do to be in a city with the most opportunities? For me, it was be willing to live in a smaller place.