Seattle is fine on power, you can pave the parts of the Mojave in California to power California instead (although tbh I think what we need most in CA is storage for when the sun goes down).

I think you can also reduce heat loss by cranking the voltage up, right? I imagine that's how current interstate/cross-country power deals work

Bigger interstate wires hold more power and have a much higher thermal mass, which is fine until someone's tree shorts everything out because lines sag greatly with more heat/power