Sounds to me like you've already got a nice, simple batch on hand. For a 2.5 to 3 gallon recipe, I would recommend:
3.5 lbs of the DME
3/4 lb of the crystal malt
As for the hops, I'd use a combination of both. Chinook for bittering, cascade for finishing. This depends more on how hoppy you like it. If you are experimenting, you probably do not want it overly hoppy to distract from subtle tastes. I would recommend:
1/2 oz chinook, full boil
1/4 oz cascade, @ 20 minutes
1/4 oz cascade, @ heat shut off
1/4 oz cascade, dry hopped if you wish.
And, of course, your Wyeast American Ale 1056 yeast
I have never used flaked barley, so I can't make a recommendation. I'm certain somebody else here could. Me? I'd use it anyway, but I'd check for advice on quantity.
Allergy Warning: This post was made by a person who may be nuts
From the store: Nothing right now, how sad
Up Next: Thinking about an amber rye
Secondary: "Not as Pale as Death" pale ale (since april, man I hate bottling.)
In bottles: Lager than Life Beer, Rocky Raccoon Honey Lager, A nameless Imperial Stout (my first AG!)