Days 0 and 1 really are much of the same... get up early, hop on a quick plane flight, hang out in the United club for a few hours, then hop on a much bigger airplane for the trans-Pacific flight to Asia.
Things were a bit crowded at SFO, looks like United had a bunch of trans-Pacific flights leaving the same time, but as soon as a few 747's and 777's of people left, things got much better. As a plus, the 777-200ER's that United uses to Taipei are way better (albeit still not great) than the ancient 747-400's they use to Hong Kong. Personal TV's and in-seat power are a major plus vs. the old 747's. Food is still awful, tho.