Avoid the arrivals lounge -- it is landside and you don't have time for that. As stated you do have access to the CX F lounges, and generally there is a cabana available without waiting. The renovated cabanas are much nicer than originally though less conducive to lingering (hence fewer people using them for 5 hours at a time). The F lounge also has showers if no cabanas are available and those are nicer than most lounges.