We always stay at Hilton properties and I find the best rates by booking directly through them, there's usually a discounted rate for being a Honors member. One thing I've found though is that sometimes booking a couple days at a time can make a big difference in price and other times booking a longer stay makes a difference. I always just play around with it too see what is the best deal. Start by looking at rates for 1 night at a time then 2 nights, etc. For our July trip we had 3 nights and 1 night. If you split it up you can call the hotel directly a day or two prior to arrival so they make note of it so you don't need to change rooms.