Looking for a moderately priced hotel or guest house in Belfast in September

booking.com

Look at Premeir Inn Titanic Quarter

Another vote for the Premier Inn. It's adjacent to the Titanic Belfast Museum and is a short walk into the city center. There's also a HoHo bus pickup point less than a block away, so unless you plan to explore further afield you won't need (nor would you want) a car.

We just stayed two nights at the new Hampton Inn in Belfast. It was very nice and centrally located.