If you have the $700, I would go with option 2. I just did that trip with miles (albeit I did NRT - USA in F but BKK - NRT was in J).

BKK - NRT is on a 787 with the NEO shell seats. They are pretty comfortable for the ride, especially as a daytime flight, and I actually liked the timing - but I was overnighting in NRT. It looks like the connection from BKK - NRT - LAX is fairly tight (1 hour on a randomly selected date). This would definitely prevent you from taking advantage of the lounge.

In terms of the NRT - LAX flight on the 77W. I flew SFOHND in J on the 77W in March and it was very nice for the trip over the Pacific. It's completely lie-flat (and a comfortable lie-flat), the food is pretty good, there is a solid selection of alcohol (The Yamazaki and Hakushu if you are in to Japanese whiskey). The IFE selection is pretty limited, I was running out of stuff to watch at the end of my NRTJFK flight but I had also spent ~17.5 hours on JL over 2 days. It is 2-3-2 seating however I didn't mind this since I think it is laid out well. There are numerous JAL J trip reports that you can look at (I haven't posted mine yet unfortunately).

The menus for both BKKNRT and NRTLAX can be found on the JAL website so you can add that to your decision-making process.

I've never flown China Airlines so can't help compare it against JAL but certainly if you have the $700 it is worth it.