Answer: NOT San Francisco like you guessed. Turns out it's Plano, Texas.
From Mashable.com, "Plano, Texas, beat out both San Jose (2) and San Francisco (3) as the most tablet- (or at least iPad-) friendly city in the U.S. And despite its high concentration of both Apple and Best Buy stores, New York City landed in the middle of the pack at 42.
Toledo, Ohio, ranked dead last."
Click the link above to find out why Plano ranked numero uno.