West Coast IPA is the style I've brewed the most and it's also the kind I still make the most. I still tend to add a decent amount of light to medium crystal/caramel malt, which most modern IPAs do not. I usually do 5% to 8% crystal, but I've gone over 10% in a lot of my old-school recipes (which wasn't unusual in the early 2000s and early 2010s). Hops are, as others have said, lots of boil additions, usually with no whirlpool/hopstand (a lot of them were MASSIVE MASSIVE flameout additions, though, which is like whirlpool/hopstand but adding some bitterness and not adding as much aroma). I usually used either Columbus or Centennial for bittering, then would use other C hops for aroma and flavor: Chinook, Cascade, and once it was released, Citra (and yes, I'd use Centennial and Columbus outside of just bittering as well). Also Simcoe is a great one. In fact, Simcoe is one of my all-time favorite hops, period. For West Coast imperial IPAs (double IPAs, triple IPAs), I often bittered with Magnum.
It is kind of funny now to think that I sometimes made West Coast IPAs where there was no dry hopping, which is something I would NEVER consider in my wildest dreams now, but it wasn't that unusual back then. I will say, though, that I tended to prefer the dry hopped versions, which is one of the main reasons why I ALWAYS dry hop my IPAs now.