Look at all Hilton properties nearby and use a booking engine that's easy for this type of search (e.g. orbitz or travelocity). Sometimes the Doubletree (or HGI or Homewood) down the street is cheaper than a HI. As you are searching another booking site, make use of Hilton's Best Rates Guarantee when applicable.

Price the government rates with single occupancy if eligible.

On the Hilton reservation site, click on the link that allows you to display all rooms that don't meet your preferences.

Sometimes you can't win and you'll have to go to Priceline or Motel 6. Loyalty is not worth a $40+ difference.