Once upon a time, Tyranids were (in)famous for building a ramp with their army; Termagants giving cover to Hormagaunts, giving cover to Warriors, giving cover to The Hive Tyrant. I think with one, sublte change, that might be our best tactic right now. (until we get errattas, or an expansion book or something)
Gaunts in a T-formation up front, with the leg stretching back to the Venomthropes.
Warriors behind the Guants, to provide larger models which can actualy cover 25% of a Hive Tyrant.
Tyrant, Carnies, whatever coming up as the real punch of the army.
Venomthropes hidden as well as possible in the back.
Every unit gets shrouded, which is a 5+ save on the Guants in front, and a 3+ cover save for the rest of the army.
Come to think of it, Gargoyles might be really good, (taken in large numbers) for that front rank, as they wouldn't need warriors to start giving solid cover saves to monsterous creatures.