The sub-$600 all-in, roundtrip fares only look to be available in June and July and then they double to over $1,200. I've never been to Tokyo and while I swore off any more coach mileage runs, this one is tempting.
I can get JFK-LAX-HND for $597 total roundtrip. I'd net 15,925 Medallion Qualifying Miles and 15,925 base miles, plus:
+ 125% Diamond bonus of 19,906
+ double LAX-HND promo bonus of 10,975
= 46,806 SkyMiles, and while I don't want to fly coach, Delta is introducing Economy Comfort, which features 4 extra inches of legroom and up to 50% more recline and I'd get it free as a Diamond Medallion. Plus, Delta is flying their 777-LR on this route, which is ostensibly their nicest aircraft.
Well, by the time I finished this blog post, I convinced myself to go for it and book a 2 night, 3 day mini-Tokyo vacation for early June. I kept getting; "We're sorry. The fare for the flights you selected just sold out. Please search again to view and select alternate flights." so I had to call Delta to book the dates I wanted.
If you see a trip you like, Delta allows risk-free cancellations by 11:59pm EST the day after you book a ticket so I'd recommend booking now and thinking about it later if you want to go. For more info on pricing from other cities, check out the Flyertalk thread.









