this is my ALL TIME favourite when playing against terrans on money maps: i call it "The Guardian Angel" i get 36 Guardians, 18 devourers, 2 overlords. and all i have to do is CHARGE my terran opponent's base with the 36 guardians. while goliaths and marine stand NO CHANCE against the guardians, i get my overlords to follow my devourers to detect wraiths. and use the devourers to destroy any air units........it worked 90% of the time whereas against protoss the guardian angel doesn't work cos of psionic storm, so i usually just charge their base with zerglings and hydralisks
I usually mix various units for attack to keep my opponent guessing, but I almost always have a group or two of zerglings leading the way.
You know nothing beats absolutely pwning an enemy base with 8 groups of fully upgraded Zerglings. Theoretically you could have 300-340 Zerglings alive at anyone given time. If you send them in at different angles I don't really know what you could do to defend against it. One of my favorite things to do is divert some of the main bases forces with a side attack and then sweep up through the front it also works best if you have Infested Terrans. A whole stream of those could totally ruin your day.