Why not just offer a diesel engine? They already do this in the suburban and Silverado (all three are mechanically the same) That Duramax is a pretty good engine

And why is the gas engine a V8 and not a V6? (again, this V6 is also available on the pickup) Will the gas engine at least be E85 Flex-fuel? (its usefulness is debated, but GM has been pushing it a lot)

A diesel Suburban [or pickup] is a better choice than a Tahoe Hybrid, especially a V8 Tahoe hybrid (FFV V6 hybrid may tilt the scale a bit towards the hybrid)