Hello, folks.
Oldest child graduating college next year so taking our "Last Family Holiday" to Thailand. We'd like to spend our miles and cash judiciously to get 5 business tickets each way. We've never booked award tickets on a partner airline and so far have been stymied twice.

• Depart 18Dec2015 from PHL or NY (EWR/JFK) or IAD preferably eastbound flight
• Return 02 (late) or 03Jan2016 either eastbound or westbound

I'm a UA Plat and have ~500K Amex miles. We're holding 3 UA award tix for return (TG metal to PVG, UA to EWR; waiting to bank more UA miles or a sale for 2 more tix).
Our problem is the outbound... We saw AC award tickets on OZ metal and moved Amex miles, only to find out they couldn't be booked; AC failed to observe the OZ blackout in December! AC was nice enough to request our Amex miles be moved back; still waiting for them to show up. We then saw SQ award tickets online, but after calling they said there's a waitlist for business standard awards.

1. Any advice on best strategies to do this and best time to book?
2. Should we be calling the airline as opposed to web booking?
3. Should we pay an award miles service to do this?

Thanks in advance!