Next, are you sure it's a domestic 777? On this route, it's much more likely to be an international 777, which is 1-2-1, and features full First Suites. An awesome experience! But it requires an expensive F3 (or similar) fare, or an upgrade from a D fare at least.
The true domestic 777, if that is what it is, is just regular domestic F. Not worth the money, IMHO, unless you're used to paying for domestic F.
You need to check the seatmaps, but usually now the 777 going SFO ORD are all domestic. There are a couple of 763s that are international config, but as we know the 763 F seat isn't much better than the C seat. So as the above poster said, I wouldn't waste money if it is a domestic config flight, same 38" pitch as other first class in the UA system.