All of these are viable and potentially sensible use of Avios, though the BAH one probably is open to question in terms of value, the others are probably better bets. As ever the specifics matter here. The one to potentially add is that sometimes one-way tickets are relatively expensive whereas on Avios they are not always so. Hence if you were doing something like EDI to Thailand, as a return ticket, it may be that cash is the most cost effective way to do that, however if you were then going to do say BKK-HKG-KUL-BKK by way of a tour of SE Asia, then Avios will be very useful. Even more so in Business and more so still in Business around the Qantas network.