Looks tasty to me. I'd second the Munich recommendation (I *love* Munich malt), maybe swap out two pounds of the pale malt. Amarillo hops are a real nice complement to the Cascade/Chinook/Centenial combo, but you're good as you are.
I'm wondering if this would be considered more of a barleywine or more of an Imperial IPA. If you wanted to go more in the big-IPA direction and dry it out a LITTLE, you could get a pound of corn sugar in there to increase the fermentabilty of the wort. Your call, though, looks damn tasty as-is.