I use crystal 40L the most in APAs, but one of the things I've enjoyed is mixing it up. I've found that "layering" the crystal malts really gives a depth of flavor that I love. For example, .5 pound of 20L and .5 pound of 60L. Or, .75 pound 40L and .25 pound of 120L. I have one IPA recipe that uses quite a bit of crystal malt, and I don't have the recipe right in front of me so I"m guessing, but I think it's got about .5 pound 20L and .5 pound 80L.
I'd suggest trying something like that- it provides some interesting depth without being too sweet.