During October, the Glasgow Novotel, which is one of the better hotels in the City Centre, is doing a "3rd night free" promotion at weeknds. That means that for a 3 night stay, arriving on a Friday, the cost per person sharing a Twin or Double works out at just under £22 per night which is excellent value.
The offer also applies to Thursday arrivals but the overall rate is slightly higher at around £23.50 per night. Still a good deal though.