The main reason I'm looking at making Hilton my backup hotel chain is because if I'm lucky, Starwood will constitute the majority of my hotel stays, both for business and leisure, and my SPG Amex is going to be my main general spending card. I could even conceivably earn status at Starwood (either by stays, or by getting the Amex Platinum). Thus, any hotel chain I would use as my backup would likely not be used often enough to earn useful redemptions in a timely manner, let alone non-CC status.

That's why I'm looking at Hilton as my backup. Every resource I've looked at says that HHonors Gold is a great "sweet spot" status level that's attainable with a credit card. It's comparable to Hyatt Platinum or SPG Gold, but has the added benefit of Hilton's coverage. IHG Platinum, on the other hand, seems very inconsistent (there's an "Platinum Benefits - The IHG Lottery" thread in the IHG forum talking about IHG's inconsistencies with granting perks to visitors), while Marriott Gold/Platinum status seems very difficult if not impossible to achieve for someone who is only going to use Marriott as a backup.

I would certainly consider getting the IHG card, though, just because IHG is so big and the card is so cheap that there doesn't seem to be much reason to NOT get it. I just don't know how often I'd use it knowing that the benefits are a bit of a coin toss.