The Hilton half-price weekend rates work for weekdays in some cases provided you book no more than 3 nights at a time.
There were a few mistakes, some hotels in Europe put in all their rooms and suites for all dates - now pulled.
But the hotels have discretion as to which days they allow as "weekends", and it seems some properties are using this as an opportunity to have a genuine sale.
For low-season periods you may find this rate for all days.
For example the Australian Hiltons are available at this rate throughout January. The Perth Hilton, normally AUD220, seems a bargain at AUD92 (USD84).
Best of all the rate includes breakfast.