CPMaverick

There are actually a couple good options. The 9-wide 777s that DL and VA have on this route are above average for a Y class experience. And VA tends to have a very good soft product. VA also offers cash upgrades (bidding process)to Premium Economy and Business (space available of course). PE will be around $500 pp each way and J will be around $1500 pp each way. Not a bad way to get a J seat if you can't get an award.

VA also typically releases J seats close to the date of travel. If you found an open J seat, you could pay the award change fee and book that (assuming you have the points).

This is generally a slow travel time to Australia. There is no Thanksgiving in Oz of course, so it's just a regular weekend but so close to Christmas/summer that few Australians would be traveling. Couple that with few US business travelers traveling to Oz around this time, and your odds are definitely better than average. Unfortunately, these flights are typically full in J so no guarantees even with the favorable dates.

I don't really understand this statement. Generally deciding whether it is worth using miles depends on the revenue ticket price (cents per mile). If revenue tickets are highly priced, this makes award tickets a better value not worse. That said, there have been some stellar deals on this route lately for revenue tickets. Again, just use cents per mile as your guide (search here for what people consider a 'good deal' it's a whole different topic

NZ in economy is not a good hard product. The service can be much better than UA. Both are poor choices IMO so I'd only spend the $$ on NZ if the routing was much better.

SQ points can be used for VA. I'm not sure on the redemption rates, or how easily you can transfer points to SQ from your other balances. DL points can also be used for VA so you may be able to patch a VA itinerary together.