www.hhonors.com

The main award is 175k for 6 free nights. It's called GLONP2. You must hold an elite level to redeem this award, but Silver is a freebie level (just like at Marriott) and it counts for this purpose.

So, if you were serious about a Hilton property, I'd sign up for the HH Amex first (probably the easiest way to get free Silver status) so that when you call and talk to an agent about a GLONP2 award, you'll already have that status.

If you're really serious about doing a week or two at Hiltons, you should actually use the HH Amex for $20k in general spending - that gets you Gold, which has similar benefits to Marriott Gold.