Lots of choices but depends on what you are trying to achieve.
Do you want a mini vacation (ie. go somewhere interesting--try Buenos Aires)
Do you want to earn lots of AQD for your time and guarantee your upgrade (ie. buy a full fare premium econo fare and upgrade immediately; will use up almost all the eupgrades on RT; 26 in all; you could go to Hong Kong or Buenos Aires or somewhere where there is a sale on Prem Econo fares)
Do you just want to guarantee your upgrade on a cheaper fare (ie buy a cheaper Flex fare with R space within the upgrade window so you can upgrade immediately; in Canada will use up about 22 eupgrades on lowest flex fare for a long flight)
I am sure there are other choices too.
For me, if I really wanted to use those eupgrades, I would likely choose a mini (or full) vacation, and guarantee my upgrade on a cheaper Flex fare within the eupgrade window; be flexible about where I wanted to go but I have ExpertFlyer to check on R space).