Same dilemma here. I bought a size 11 and 11.5, although in every other Air Max 90 I've gone with the 11.5 and have been fine (true size is 11). My rule for Air Max has always been 1/2 size up from my true 11.
With these, the 11 is a bit too snug for my liking. The 11.5 is too roomy, as the shoe slips off my heel when I walk--this NEVER happened with other 90's. Width wise, the 11.5s fit perfect, but they're mad long. The 11s fit perfectly length wise, but are too tight "swoosh to swoosh". I need a size 11.25.
So now I don't know what to do. I could take the insole out of the 11 and they'd probably work fine, but I'd be sacrificing comfort. Or I could try to find some thicker insoles for the 11.5s. Honestly, I'm close to selling them both and copping another pair of HOAs and 2010s.