Rewards4all
The problem with trying to use Rewards4all for last minute flights is that the chances of actually booking an available flight seem to be minimal. Even trying to book months ahead, you have to accept flights that are inconvenient (perhaps one leg will suit, but the return will then be on the wrong day). And because you're looking so far ahead, the majority of the fare is likely to be taxes and charges anyway.
I've used Rewards4all points for an Economy Plus flight, but it wasn't good value. I didn't have any luggage, and there was no time to use the lounge. I could have booked a full-fare Economy flight for only a little more. The main benefits were being able to select a seat, and a voucher for food and drink. Not much, really. In theory you can change the flight without charge; but only to another "free" return flight.
Also, several routes have NO Rewards4all seats available, ever.
I rate the scheme as pretty mean overall. Although the BA Miles scheme seems rather stingy too (to say the least). So I suppose we have to accept that these "loyalty" schemes are simply marketing ploys with little substance behind them.