All of this is a bit of guessing (not experience), but...
They
are angled, but to be honest I find they're comfy enough. Of course, if you can't sleep on one, you can't sleep on one - too bad.
There's a lot of sentiment out there (particularly from "distinguished" FF bloggers) who believe that the only way to go in J is a fully flat seat parallel to the floor - anything else is criminal. Personally, I think that view is over the top and dismissive. With a bit of adaptation, it is not difficult at all to be comfortable on an angle flat seat, and TG J is no exception.
Having flown in TG J before, I think it's adequate. Leg room is quite good.
Luckily, BKK-NRT is a long-ish sector (about 6-7 hours), so there's a chance to get some decent rest (unlike, say, BKK-ICN, which is similar to an Australian transcontinental red-eye Eastbound).
As far as J on *A
within Asia is concerned, I think none of the airlines offer flat beds. Not sure about the Chinese carriers. If you can book on SQ's longhaul aircraft (77W, A380), their J will be flat, but otherwise their regional J is angled flat, too. NH I believe is angle flat.
Note that for getting
to Asia, NZ has flat beds in J in herringbone configuration (the latter being another debate on its own). However, you must fly on the 777 services to get these J flat beds (NZ "Business Premier"). The 763 services have Millennium style J seats.
Yep, you'll need to make your own way to SYD.
Trying to tag off the UA flight between MEL and SYD is just too risky IMO. I don't want to get into an argument as to whether UA have the proper rights to convey passengers unconditionally between MEL and SYD, but given that it's only
supposed to be for pax who must connect to or from MEL on the same UA service, I wouldn't start doing the very American thing of pushing the legal boundaries and fare rules (and subsequently complaining about the injustice of it).
Ho Chi Minh City is SGN.
As
MEL_Traveller mentioned, this breaks the "not a *A hub" rule, so you may have trouble trying to create this itinerary.
You can get creative within some reason. You can put in a stopover here or a transfer point there, but if your itinerary starts to look ridiculous then it mightn't pass mustard.
The idea of creativity is usually a bit easier with longer itineraries, because on shorter ones it's much harder to believe that you can slot cities here and there.
If you are interested in going to SGN for a side trip, you may have to consider your stopover at a nearby Asian city / *A hub, then finding a cheap tag flight to SGN.
You can try your luck on a few things.
North America (over the Pacific then South) is the obvious choice, if only that UA wouldn't be the first airline that I'd run to, especially when burning points for J or F.
The more novel choices are:
- SA via South Africa, viz. something like MEL or SYD -AKL-PER-JNB-GRU. J only.
- Go via Europe. LH, LX and TK all fly to GRU from their respective hubs.
- SQ and CA fly to GRU from their respective hubs, but they make a stop along the way. Not sure how US would price / ticket this up (more important about how many points you get charged).
- TAM Airlines (JJ) are, for the moment, still a member of *A. Many options to fly into either GRU or GIG from North America or Europe.
Generally you've got a better chance getting into South America via GRU (Sao Paolo) or GIG (Rio de Janerio).
I can see availability on the longest haul flights being at a premium, especially the F options (I would, however, hypothesise a better chance at an F seat to South America than a regular TATL).