sm2, I'm having similar issue with where to go once we get to BKK. Nonrev decisions are REALLY hard. We have 10 days and I only have 3 nt luxlink pkg so far. Keep in mind if you do China, visas add up--that's most of the "budget". I know what you mean about homestays for Asia--so many have only 1 room (I was poking around a site yesterday and found only 1 in Seoul for 5 pax and that was city)
I hear ya on seats for 5--our 4 buddies get around very well overseas but are quick to change routes on their own if I tell them where it looks better. Again, good luck!