Long time lurker, first time poster.
First of all, awesome work to all the mappers. I can't do that, mapping all the mountains and features, matching them up to screenshots, frames from trailers, etc. So thank you, and GET A LIFE! J/k
Secondly, as my name suggests, I'm a native Californian, a native Southern Californian at that, a not-so-happy frequent traveler of the 405, the 215, the 91, the 710, and the 5. I'm astounded with how much this San Andreas looks and probably feels exactly like the LA Basin. The smog is laying perfectly in the valleys, the cloud cover is appropriate and even the glare from the sun is dead-on.
Which brings me to a final point. They put a lot of effort into this. We know how much detail we'll find in the city of Los Santos, down to the brick patterns on some obscure building next to a less obscure bridge (let's face it, they're iconic.) We know that detail extends to Sandy Shores, almost exact mock-ups of real-life buildings, landmarks, and even people's homes. Why wouldn't that level of detail extend to the outer limits?
I believe it does. And I believe that if we could find real-life matches to locales in the countryside, places on the 5, Pacific Coast Highway, the I.E. freeways, Historic Route 66, we'll get an idea of where exactly Rockstar went, and wants to take us.
So as nothing in the mountain pass screenshots looks anything like the mountainous regions near LA, it's safe to assume that area is based on something much further away, and not Mammoth Mountain, more like Yosemite, honestly.
If we could match Paleto to a real town, where would we look? Looks like a mountain town, no?
Grapeseed doesn't look like it would be in SoCal. I think it would be in the foothills around the Central Valley, which are getting closer to Yosemite. Unless it's supposed to be Oxnard, and it doesn't look like it would have vineyards either way. The rolling hills in the bicycle race shot from the gameplay trailer would be more conducive to grape harvesting. Where have we decided that is?
Los Angeles and the surrounding areas eh. There's a lot more to this, more to explore, more to map. I'll gladly join in the fun.