Question about specialty malt and recipe

I have a quick question about crystal malt and then would also like some comments on the recipe I made.
Is there any point in using two different kinds of crystal malts in a brew? And by different malts I mean like using 3/4 pound 40L Crystal malt and 1/4 pound20L or some other combo of differnt colored crystal malts. In the books I have read they say that each L has different flavors.
I am planning on making on American Pale Ale, Extract plus specialty grains tomorrow and here is the recipe I have made up so far.
Target gravity - 1.052
5.5 Pounds Muntons Plain DME
1 Pound specialty malt
1OZ Cascade Hops - Boil
1OZ Liberty - Flavor
1OZ Liberty - Aroma
I guess doing this I have one more question. What other specialty malts work well in a APA other then crystal. And also if you other comments please let me know as this is my first time with out using a kits.

You can use different amounts of crystal malt to attain certain SRM's/color but if you substitute you wont be able to match the unique flavor of each malt, I have a Baltic Porter recipe that uses two different caramel malts and have subbed a higher amount of a lower Lovibond in place of the higher one and the difference in the taste of the final product was noticeable.

It depends on what you're going for, but you could easily make a great beer using only one malt. The quick run down on the crystal malts is that the lighter (i.e. 10L-40L) one have more honey flavors while the darker ones (i.e. 80L-120L) have more toffee and raisin flavors. As for whether there's a point to adding in BOTH 20L and 40L, I guess there's only a point if you see one in the beer you want to create. As a style, pale ales vary from being drier and having a more biscuity malt flavor to being sweeter and more carmelish until it approaches an amber ale. 40L would give more carmel and if I were to use the 20L for a lighter, more biscuity version I'd probably just use victory malt instead. Jeff Zainasheff gives an american pale ale recipe like this that uses .5 lbs of wheat DME and .75 lbs victory malt that looks pretty damn good. Obviously, the choice is yours. Hope that helps. If not, I'm sure you've run across this:

https://www.homebrewtalk.com/f12/ingredient-guides-25383/

Also, here's a link to different recipes for "American Ales" from this website. Search through them to see what specialty grains they're using. EdWort has an extract recipe for the Bee Cave Haus Pale Ale, which I've heard is delicious. Happy brewing. American Ale - Home Brew Forums