No discounts at regular Hilton hotels.
You can convert your HGVC points to Hilton Honors points and book a room that way. Some people seem to find that attractive, personally i prefer to use my HGVC points for a timeshare as I find better value that way.
You can get a discounted cash rate via "Open Season" booking at HGVC resorts. Believe that is available 30 day prior to booking.
For me at least, AAA seems to offer the best discount with Hilton. I am sure other program like AARP, have similar discounts.
Chris