I guess most people would think I'm a bit odd (!), but I just booked a trip on the basis of getting access to the OneWorld lounges (BA,CX, QF) in LHR T3.
I also wanted to go to somewhere in Italy, but had no particular preference (apart from not Northern Italy). So, looking at BA's destinations in Italy from T3 I chose PEG (Perugia), as I'd never been there before and it seems quite interesting, and it was also quite inexpensive (AUD$114).
I'd previously panned to spend the time in London...