I'd say the flight prices are good.
Might be worth checking if PAL will upgrade your second leg - I got an upgrade from MNL-DOH for about £310 last year from an AMEX booking. Korean Air is a nice airline - always enjoyed travelling with them and I try to find ways to travel with them more...
I know people who have paid those kind of prices and it will give you exclusivity and a kitchen, but personally, I think it's overpriced. To put it into perspective - how many months of local wages if $1,500. If you go into the Thai Airways forum you might find better advice there.
Are you going to use the kitchen facilities (if you intend to eat out, why not hotel suites?). Also, Pattaya from recollection is a beach type place a distance from Bangkok. Are you wanting to be in situ for 2 weeks or do you want to explore Thailand a bit?
It's just food for thought here.
I will check the itinerary later as my wife is wanting to do a Vietnam trip and I'll get back to you.
If I get my way I would expand it to an IndoChina (that's the name to the old French Colonies of Vietnam, Laos and Cambodia) - we very much enjoyed Siem Riep and would love to go back there for Angkor Wat. Laos is very much off the beaten track - only worth doing for ecotourism. An example itinerary is here:
https://www.indochina.tours/package/...Zsb4wQ72GhhYSI