Comfortable is warmth, with a nice breeze and the smell of bagels and muffins, and a cushy chair with armrests that are broken in but not suspiciously stained. Comfortable is being inside, not out, today.
Comfortable is overhearing bits and pieces of pleasant conversation, seeing the smiles and feeling the familiar lulls, and knowing that around you people are engaged and content and coping. Comfortable is steady productivity, head bent over the book and fingers tapping the keyboard and the smile as results accumulate.
Comfortable is hipster music playing loudly but unobtrusively from downstairs into the loft, and a soft but bright light from the windows overhead, leaving no shady corners and unilluminated words. Comfortable is the hiss of steamed milk and the clack of ice, and the safe slow atmosphere of meeting.
I've come to this conclusion: comfortable is a coffee shop.