Guangzhou can be quite expensive. Don't visit in April or October when the main trade fairs are on, as you may have to pay even above rack rates. Sweltering July and August are popular with tour groups. However, from November to March, rates drop, with a further dip in December and after Chinese New Year.
This is one of the last cities where cavernous hotels with innumerable rooms and endless facilities have survived in any numbers. These are designed to serve the vast numbers of business people attending the main trade fairs in the last 2 weeks of October and April. These have an effect on room rates as far away as Hong Kong, and the major hotels, despite their cavernous size, are likely to be full in that period and offering no discounts. Otherwise, expect to cut 20% to 50% from the prices quoted, although major hotels also add a 10% service charge and a 5% city tax. Lesser hotels conform to normal Chinese standards by not adding service and including city tax in the quoted price.