I didn't find a "C9" setting in the BIOS that was mentioned in the first link, but there was a "C6". A Google search
indicates this is one of a series of CPU sleep states. I disabled it. I also installed the proprietary graphics driver, fglrx, for the Radeon HD 6320 graphics chipset with the hope that might fix things.
Alas, these changes haven't completely solved the problem. Suspend works fine three or four times -- and then it doesn't resume. I have to unplug the power supply and briefly remove the battery before the Eee will boot again.
At this point, I assume it is a hardware issue; some obscure bug in the BIOS. I will try writing to Asus support, but if I tell them I am running Linux I expect no help.
The disappointing thing for me is that suspend working flawlessly on my previous Eee, a 1001 HA.