That's a rhetorical question. I stumbled on this gem today while looking for flights to NYC in April, and I was originally trying to get there on miles. As is usually the case, United had no availability at the saver level, so I started looking at standard awards. I know! But I'm kind of hard-up for cash these days, plus I really don't want to do a transcon in economy if I can avoid it, and both of these are triggers that lead to me entertaining dumb mileage redemptions... such as 50,000-per-leg domestic business class awards. That's when I saw that United was flying a 777-300ER on the SFO-EWR route, which would definitely be an upgrade over the normal 757 p.s. seats they usually offer. After talking myself out of spending 50,000 miles on a 5-hour flight, I searched for revenue fares and found fares on that flight for a semi-reasonable $687. Between the United gift registry credit I have from my two Amex Platinum cards and the $250 airline credit from the Citi Prestige that I haven't canceled yet, I can just about get there. I think I'm gonna do it! I've never flown on such a new plane before, and I think it would be neat to check out Polaris after all the hoopla United has built up around it.
From what I could tell after digging around on United, transcons on the 777-300 start February 16th and run through May 1st (availability varies by day, since there are flights in both directions). That's a pretty big window to try out the new seats before they go long-haul only. I also don't know if any other cities are getting the plane, since I'm pretty selfish and only research flights that specifically interest me.
EDIT: Uhh duh, The Points Guy wrote about flights starting on 2/16 a long time ago, I just forgot about it. There goes my scoop. I don't think TPG had anything about when the flights would end, though, so I'm good for something at least.
One note: this flight isn't marketed as a Polaris flight, so my assumption is that it doesn't include entry into the Global First lounge at SFO (which will become a Polaris lounge sometime soon). I also don't know how much of the soft product will actually be included, although I'm mostly curious about the seat anyway, so I won't be disappointed if they don't offer any of the normal long-haul amenities. (Plus, I'm flying Global First this summer, so I'll get to see the ORD Polaris lounge and all the fancy Saks Fifth Avenue stuff pretty soon anyway.)
Anyone have plans to try out Polaris seats on this route? I'm pretty excited to book my flight, and I promise that I'll wait 6 months to write a review of it, so it's no longer timely by the time you read it.