With cards, your best bet for the other 2 channels are omni's. No real reason to run 4 channels of cards, although it's useful when you're just going to use one of the sources, and not a blend of both.
Alot of times I just try and mix and match wildly different polar patterns and configurations. Mid/side with omni's NOS sounds great, as does an XY pair of cards with omni outriggers, etc.