Yes, complimentary e-upgrades are valid on all domestic routes, including nonstop transcons. However, the Flagship-marketed routes like LAX-MIA on 777 equipment (with lie-flat seats in premium cabins) often have plenty of customers willing to pay for the premium seats. So, do not expect a complimentary upgrade to be available. Using miles+copay or SWU might increase your chances of an upgrade, or just buy up to Business if it’s very important to you to have the premium seat.