I personally wouldn't use special roast or crystal 120. I thought your first recipe was pretty good, just boost the caramunich and drop the base malt accordingly:
Pilsner or pale 4.25 lbs
flaked corn 2 lbs
vienna 1.375 lb
caramunich 3 lb
roast barley 2 oz
You can play around with it. A small vienna or munich addition is optional, but I really don't think it will have much impact. You can use different types of crystal malts, but try to stick to those in the med to light range, say 20-60L. As for the roasted malts, keep it to an ounce or two, but use whatever you want.