The OP said he used Armadillo tires - there's not much that's more flat-resistant than an Armadillo, unless...I know there's several different versions, unless he got a version that was less flat resistant than the Armadillo I'm thinking of.

From what I've read the only tire I know of that might be tougher is the Schwalbe Marathon Plus (they have a Marathon Plus MTB version to). But even that's a matter of some debate - both the Schwalbe's and the Armadillo's are in the "flat resistant as it gets" category.