There's an ongoing debate about if hop bitterness even has a unique character per hop. When people think of hop character, they think more of the flavoring and aroma additions.
A guy in my brewclub just put about a cup of boiling water in styrofoam cups with a little bit of DME and added a pinch of about 25 different hops to 25 different cups. It was a little more controlled than that, but you get the idea.
That was a pretty good exercise, IMO.
I agree, though, that the descriptions of hops are pretty good these days. I tend to keep citrusy/fruity/floraly hops matched together, and bitter to the IBUs of the style or underlying style (if I'm experimenting). I would then do the same thing, but keep resiny/earthy/spicy/woody/piney type hops together.
That always works for me. Besides the two kinda group designations I made above, most hops are not drastically different, they are a pretty smooth spectrum along the same continuam, and when you are brewing to a particular style, it's pretty easy to research what hops are best for that style.
Hope that helps!