You can safely compare the Tahoe Hybrid depreciation to that of a Tahoe LTZ. They both have approximately the same MSRP new and are comparable in their used sale prices.
I bought my 2009 used in 2010 with 12k miles on her for $39K, and sold her a year later with 25k miles for around $35k.
---------- Post added at 02:03 PM ---------- Previous post was at 01:42 PM ----------
Btw, I honestly would advise against buying a new one and suggest going for a low mileage barely used one. Reason is that there are two elements that are going to be adding to the depreciation of a brand new one. First, the whole full size SUV line is about to get released with the new redesign, and second, they have announced that the hybrid line will cease production when that happens. The latter element might actually help preserve value although that's hard to tell ... given that you live in Cali and know the volatility of gas prices, that may indeed be the case.
Still, buying a brand new vehicle just as a new version is about to get released is never a good idea, unless of course the dealer heavily discounts for this fact. That usually happens when the new versions are on or near their lot.