For hoppy beers, I almost always do FWH with the first hops addition. I guess it's because, well, why not? I fully get the bitterness (not like a 20 minute hops addition like some say), and it is supposedly a "smoother bitterness" although I couldn't say that for a fact because I've never done two identical batches side-by-side. I do like the effects, and that's all that I really care about anyway!
I calculate the IBUs as a 75 minute addition or 60 minute addition, depending on the length of the boil (usually 60 minutes) and that seems to work just fine for me. I use "good" flavored hops like amarillo, centennial, etc. But I like chinook very much and have used it as well. I don't pick up any discernable hops flavor, like I would with a 20 minute addition, but I don't pick up any harshness, either.