Giorgio's has changed quite a bit. I think since one of the sons and his buddy took over. My ex-GF, who was from the East Coast, even said that it's very close to the real deal.
I've heard of Gaspare's but have yet to make it over there. Isn't it somewhere deep in the Richmond District, near 43rd Ave or something like that? There are a ton of new places in the Mission District in terms of good to great pizza, but with over 3,800 restaurants in such a small town, it's become a tough choice on occasion.
A couple of great pizza joints are across the Bay Bridge - Zachary's & Pizza Rustica.
Edit: Correction. Just saw a photo of Gaspare's restaurant front. I have eaten there, actually. I used to live right around the corner! Unfortunately, I can't remember how it was, it's been so long. Need to go back and check it out again.