I love coffee tree roaster, I go to both the squirrel hill one and shadyside one. The shadyside one is larger but there are often no seats left. More younger people doing work or catching up with friends there. Coffee tree roaster is my go to studying spot since they open til midnight. I love their drinks as well, they have good mocha and black tea. Also if you get their tea using their glass, they do free refills for you which is amazing. Everyone is also very friendly there. I have many interesting conversations with random people there. It does get kind of loud sometimes. The only complaint is the free wifi only last two hours -_-