Good thread.
Looking at a Silver Sea (private charter) 7 day cruise for late Oct ... priced at around AUD$20k (US$15k) for two suites. 1 x Deluxe Veranda & 1 x Explorer. Seems like a decent deal.
Have been able to secure 4 x QF award seats SYD-SCL-SYD (2xJ & 2xPE) to ice the deal.
Thinking - just do it!