I'll give IHG credit for generally having award availability even when rates are high. It's often some weird local event that you aren't even aware of that causes small-town hotel rates to spike to their maximum...in these cases, I've still been able to snag 15k-25k one-nighters at HIX or HI. Simple awards that kept $150-200 in my pocket.

At the other extreme, I've generally observed IC having availability in the 40-50k range in cities even when top hotels are going for $400+. Haven't booked one yet, but it's nice to know that they don't always game the system and make awards unavailable.