Without being able to offer a specific example, I often use Google Flights. I set the date as same day return, select the cabin as business and limit the airline to 'One World'. I'll then scroll around the map looking if something is interesting, and if prices don't look good I'll change the date.

I often do this for some lounge trips, and occasionally an overnight stay. I find the tool great to visually see the price on the destination. You would need to calculate your tier points on the BA website, but you probably have an idea of 'distance' required (e.g Malta, HEL).

Note - This also assumes you are paying cash, not reward. It also is best for Point-to-Point flights rather than connecting.

https://i.imgur.com/7vlxTMw.jpg For Example