Now that United has loaded its first 787 into the schedule, Denver-Tokyo beginning March 31, you can see the seatmap for the aircraft by walking through a dummy booking on the website:
There are 36 business class seats, 63 economy plus seats (presumably rows 16-22, not highlighted on the seatmap), coach has been announced as 120 seats though the seatmap would appear to show 135 seats — presumably some of the blocked/unavailable seats aren’t. They clearly haven’t put the finishing touches on the seatmap since economy plus isn’t so-flagged.
Nine across in coach seems tight to me, considering that All Nippon and Japan Airlines are doing eight across with their 787s.
It’s notable that Denver – Tokyo is announced as the first 787 route for United, they had previously indicated they’d inaugurate the 787 on Houston – Auckland. But United claims that would no longer be viable if Southwest gets permission to fly internationally out of Houston-Hobby. That’s a silly claim of course. United doesn’t want the competition, and wants the government to keep that competition illegal. But Southwest certainly isn’t going to fly to New Zealand. Their proposed international flying won’t affect the viability of an Auckland flight. Certainly Southwest’s international flying out of Hobby won’t be a detriment to United’s domestic flights at Houston Intercontinental that would feed the Auckland flight. But as part of the posturing, and at least for now, Denver – Tokyo goes first.