I'm planning a trip to Ireland later this year (me + one other person) and am considering using points to travel in J. The first two options that I've found have connections in Europe (so J is in a longer, 10h or so segment), while another one has both segments split pretty evenly (~4h30m and ~6h30m). The latter also happens to have the lowest fees out of all three options I've found so far. While it's nice not to pay more fees than I have to, it does make me wonder whether we'd get much value out of the J seats considering the shorter time spent in them.

Generally speaking, how long does the flight have to be before you'd consider upgrading? In other words, is there a minimum length where you feel that you're getting good use of the extra amenities?

For me, it's pretty low. About 3 hours max if I'm not on a widebody with two seats to the outside rows. If I'm with one other person, I can stand the 2 pair seating for much, much longer since it feels more private and you can put up an armrest, get up any time needed, share space and just feel more comfortable . I did so much economy flying for work where I felt trapped on a row with strangers for 5 or 10 hours and just can't do it on my own dime anymore.

On international flights, I always price out both economy and J or F and see what the difference is and go from there. If the trip is short, I'll be more apt to want to get good rest on the flight. And if the flight it really long, I'll look a lot more for an upgrade. Like flying to Australia. I wouldn't do it in the back. Just no. Europe, I've done plenty of each and have been fine most of the time. Economy an being expected at work the next day is a no-no though. I'm not one of those lucky people who handles jet lag well.

So the choice is SAN-<East Coast>-DUB vs. SAN-<European hub>-DUB?

My first question: is there F availability on the transcon? If not, then I'd eliminate that from consideration.

If so, then it would be a question of timing and duration. Would you rather give up more of your departure day or more of your arrival day? Guessing the itin with an east coast connection is shifting a few hours earlier, but maybe has the shorter total duration.

I've done LAX to Australia in Y before and while that wasn't the most comfortable flight ever, I did get there without issues. It also helps that I generally don't sleep well (or at all most of the time) on planes in general. I've also done transcons in Y on many occasions without issues, which aren't that much shorter than the shorter TATL flight mentioned in my OP. I imagine the answer for me would be a lot simpler if I had a lower tolerance for transcon.

I've been looking ex-SAN and LAX. The options I've found so far:

• SAN-LHR-DUB on BA (but with something like $1200 per person in fees, so I'm trying to avoid this if possible)
• LAX-CDG-DUB on AF (half the fees of BA)
• LAX/SAN-YYZ-DUB on AC (the option with the lowest fees)

To answer your question, it looks like there is in fact J availability on at least LAX-YYZ (on an 787, no less), but it's two red-eyes in a row. There is apparently also LAX-IAD-DUB on UA/EI but the UA segment is in Y. I'll have to play around with dates some more to see if I can optimize the last option on the above list more.

A short EI segment probably isn't worth the J miles. I love EI for the ability to use a fairly small number of Avios to get the family to/from Europe in Y (13,000 per person off-peak from Chicago with almost no fees) but it's always seemed like a poor value for J.

The AC options would be attractive to me because I enjoy visiting Toronto in general. Always a fun place to spend a day if your schedule permits a long connection like that.

There is some flexibility (within reason), so we may be able to swing a day in Toronto. AF could be interesting too as LAX-CDG is on the A380 (which I've yet to fly), but I'm not sure how I feel about angle-flat seats. Various video reviews seem to be fine with it though and if I'm not going to be getting much sleep anyway...

Anyway, it sounds like there isn't a hard and fast rule for how long one should fly before being able to justify upgrading. For instance, going through Toronto might very well necessitate J even on the relatively short 4-5 hour transcon leg considering that one may need to be awake the entire day afterward before the next leg.

Once in a while, I book the extra night. Other times, it's the lounge or a lounge chair by the pool.

I've been in Y for LAX-SYD-SYD, IST-JFK, and similar flights and I actually managed to survive unscathed. So I guess my answer is somewhere over 14 hours. And at a typical cost difference of thousands of dollars, probably way over.

My threshold is for duration of 0 hours and longer buy J or F and don't fret about upgrades or worse, wind up flying in coach for any amount of time.

I'm the reverse. On a TATL I'd rather pay the extra night and fly in Y than fly J only to loiter around a foreign city with my luggage for hours until I get get into my hotel room.

My upper limit for Y is 8 hours but I don't mind longer trips if spit into two shorter flights. It also depends what I'm doing when I arrive. Y is easier to tolerate if I don't have business obligations upon arrival and my hotel room is waiting.

I don't know about your flights in particular, but usually flight from US to Europe in J is lie flat seat. But if you have a connection in Europe, the 2nd leg is NOT lie flat seat. For our last flight, it was not even a bigger seat. They just sit 2 people in 3 seats leaving the middle seat open calling the room "your space" to share. I am not a big person so the empty middle seat doesn't do anything for me. I do get a free meal though while the economy class in the back did not.

5 minutes. Literally.

It depends. I can survive a Y flight to Europe with family. Which is good, because finding 5 J together is impossible, even if I thought my kids would appreciate and value J. By myself or with one other adult, I'm almost always going to try to find J and usually will be willing to move dates around to get it.

But I would never spend J miles to fly a good chunk of the way there in Y. I could live with SAN-LAX or CDG-DUB in Y (with or without the blocked middle seat), but there's no way I'd fly an itin that had a 4 to 5 hour transcon in Y if I was paying for J.