Two Zero Three is part of the sorta-new Virgin Hotel, in the North Loop and just a stone's throw from the Chicago River. Designed as a combo coffee/wine bar and with long hours, this is a great spot to work from day or night - open from 6:00 AM to 11:00 PM, seven days a week. Winter hours are 6:00AM to 7:00PM.
WiFi here is excellent, as patrons can use the hotel's network. The shop is set off from the main lobby, so there isn't much hotel traffic. Almost every seat in the house has an outlet, and staff is super-friendly. They're here not just for hotel guests, but for locals as well. (And any coffee shop with Cards Against Humanity sitting on a table must be pretty accommodating.)
In the evenings, they shift to wine bar mode, but still serve coffee. Energy level goes up accordingly, so working here might be difficult for some during those hours, but it's also very social, and they have 5:30-7:30 PM "Mingle Mondays" with free cheese and other winey appetizers.
Background music is blues and soul, but not just the standards - maybe the best playlist I've ever heard in a coffee shop. (I didn't know Stevie Wonder ever did an awesome cover of the Beatles' "We Can Work It Out", and I heard a great soul version of The White Stripes' "Seven-Nation Army" that I now HAVE TO find.)
Food selection isn't much, a few bakery items and some fruit, but there's a restaurant connected to the hotel. And for a hotel shop in Chicago's Loop, the prices are more reasonable than expected, including free refills on drip coffee.
This is one of those places that you hope nobody finds out about because it's sooo great. So, you're welcome. :)