I consider myself a huge fan of American IPA's. I have tasted more comercial examples than I can recall and brewed, and brewed until I finally think I figured this thing out. I will share my thoughts on what makes AIPA so good......
#1 Finishes dry, very dry, often times assisted with sugar in the grain bill
#2 Very simple grain bill, VERY, VERY limited amount of cyrstal malts and almost never specialty malts
#3 Heavy dose of pacific northwest hops in the last 15 minutes of the boil and a huge dry hop. Varieties include, but are not limited to, cascade, centennial,chinook, amarillo, warrior, columbus, summit, willamette, etc..etc....
#4 Yeast can help add to fruity aroma and flavor or can be completely neutral, either way it needs to be a dry finishing strain. WLP007 and WLP001 are great examples
#5 This beer should not be dark, not syrupy and have no dark crystal malt (raisin, plum) flavors. I have tasted a few examples (one from Abita comes to mind) that are fairly dark, caramel driven so called IPA's.......heavy crystal malt and hop flavor aroma seem to fight each other
#6 I have tasted numerous commercial and hb examples that have a very complex grain bill, the richness and maltiness that large amounts of crystal and specialty malts add to a beer create a heaviness and cloying complexity to the ale that is just to heavy.
This all being sain here is a list of commercial examples I find to be exemplary:
Rogue Yellow Snow IPA (I consider this a benchmark...super dry, hop forward...delicious)
Sierra Nevada Torpedo
Boulder Brewing Mojo
New Belgium Ranger ( malt, sugar, hops, water, yeast....it's done well)
Sierra Nevada Celebration Ale