Central business districts look appealing on the map because they are in the middle. That is their only virtue. Almost everything else about them is bad.
CBDs empty out at night. The restaurants close at 9 PM because their office-worker lunch clientele has gone home. The streets feel dead after dark — not dangerous, just sterile. The hotels are designed for business travelers, which means chain properties, uninspired breakfast, and a clientele that disappears on weekends, taking the life of the building with them.
CBDs are rarely walkable in any meaningful sense. They are walkable for office workers between their office and the nearest lunch spot. For visitors trying to have a city experience, they are dead zones that you will spend your trip leaving.
Examples you should avoid: the City in London (beautiful architecture, no life after 6 PM), Downtown Washington, DC (closed on weekends), Frankfurt's banking district, Makati's Ayala business strip (convenient but lifeless), Singapore's Raffles Place after dark.
The alternative is always a residential neighborhood adjacent to the CBD. Shoreditch instead of the City. Mount Pleasant instead of downtown Vancouver. Poblacion instead of Ayala. Kreuzberg instead of Potsdamer Platz. You will pay less for your hotel and have a much better trip.