If you are in the area, I like the atrium in the IBM building (~57/Madison). There are bajillion coffee shops you can easily find, all very crowded.

(or, if you are in NYC a short time, stop working! See NYC)

Besides the obvious Starbucks choice[1], my personal recommendation: PieFace. Their cafes are throughout midtown and have good coffee + outlets + seating + great food (Australian meat pies and pastries).

They claim to have wifi but I usually use my phone's hotspot.

1 - for those who want (need) Starbucks, the one at 39th and 8th Avenue has tons of room on the second floor seating area.

Thanks all for the recommendations. I also found the CapitalOne 360 cafe to be pretty nice on the second floor (bonus: TV for world cup games :)). Interest is a bit slow, but the area is nice. I'll check out the other recommendations. I'm also down to meet up, I'll be here until Wednesday (traveling from SF, where I worked at a Startup there)

I'm here right now with a friend at We Work 222 Broadway, Fulton. Seems like a pretty place to work and chill. Spent the day looking for other co-working spaces and narrowed down to this one. Wasn't too keen on doing the coffee shop thing.

NYPL on 42nd st and 5th ave. Free wifi and incredible architecture. Plenty of quiet spaces to use. Also a small coffee shop inside.

The Met museum's cafeteria. You have to pay to get in, but how much is up to you.