I just did some checking on a random date for SFO-BKK. UA gave me W class to HND and then onwards to BKK on the NH 787 for $1691 Round Trip. Eva Air has their Evergreen Deluxe class available for $1849 all the way through SFO-TPE-BKK. Cathay is available in Premium Economy for $2150 all the way SFO-HKG-BKK (all in PE even HKG-BKK).
There is no valid comparison between UA E+ and these real premium economy products. Real premium economy products are comparable to UA domestic first class.
If you're willing to risk it, you can even fly Philippine Airlines for $3000 in business class the whole way, although I'd take a pass on this.