I probably spend about 75% of my time at the Roasting Plant. It checks all of the boxes (fast WIFI, plenty of outlets, lots of light) and there's almost always an open table. It can get a bit noisy when the coffee is grinding, so I typically bring my big noise-canceling headphones if I'm going to hang out here. Also, they only have sweet snacks so if you're looking for a midday meal, you might have step out for lunch (but you'll probably be able to get your table back whe you're done).
Bakeshop by WOOPS!
Sadly, the Bakeshop closed down a couple months ago due to a fire, but it should be re-opening soon. It's one of the most peaceful spots to work and there's usually plenty of room. I like to sit at the window seat so I have plenty of table space and can do some people-watching when I need a break.
Toby's Estate Coffee
You have to get to this hipster coffee shop before 9am to actually get a seat, and it can get pretty hectic around midday, but it's a bright open workspace with great food (try the avocado toast) and a quintessential Williamsburg spot.
High Line Hotel
The best thing about the High Line hotel is that you can actually work outdoors since there is WIFI in both courtyards. It's my favorite place to work if it's really nice out, though you may be asked to move to the back courtyard if they get busy for brunch. If the weather changes, you can always move inside to the cozy lobby (but there aren't any tables; just big sofas).
NY Public Library
I love working out of the Rose Main Reading room at the NYPL because it's extremely quiet and you get tons of table space. The downside? There's no food or drink allowed (though sometimes they'll let it slide if you bring in a coffee tumbler). If it's a nice day and you need a break, you can skip out to Bryant Park where there's also free WIFI and plenty of places to eat.
The Ace Hotel lobby is dark and cozy, and a perfect spot to bunker down on a cold day. It's a very popular workplace for occupational nomads, so be sure to get there early. In the evening, the lobby turns into a bustling bar so you might have trouble working (but stick around for a pickle-back shot or two).
There are six think coffees around NYC, but I typically go to the one on 8th avenue. You won't have much trouble finding a spot to work, unless you really need an outlet (there are only two). Most people work in the back because it's quieter and the tables are bigger, but I prefer the front so I can be near the window.