My favorite stratagem is overwatch, because my wife automatically hits, thus negating the main downside of the overwatch mechanic. She's so cool.

>You can add one new unit to your army
bikes with mounted flamers.
airspeeders with mounted flamers.
long range flamers, like 24 inches, and the model has a scope on a flamer.
I would also like an assault vehicle for sacresancts/repentia to charge out of, similar to a land raider, and the giant tank model would allow GW to make a moving church on wheels/tracks.
I also want a models of some sisters operating long range artillery or heavy weapons, like IG's heavy weapon teams or bombards, or maybe even something like a basilisk.
I would also enjoy the Corvus Blackstar with churchy bits on it for a faction flavored flyer.