Coffee Room is the kind of place that could exist in any European city — a well-equipped espresso bar with a small but serious selection of single-origin coffees, reliable espresso-based drinks, and the sort of comfortable seating that encourages staying for an hour. It is on or near Krasniy Prospekt, which makes it a useful stop during a walk through the centre.
The staff know coffee and can explain what they're serving, which is not universal in Russian cafes. There is usually food — pastries, sandwiches, soup — though the coffee is the reason to come. Good Wi-Fi and enough electrical sockets to suggest they are comfortable with people working there. A useful base if you are navigating the centre on foot.