It is getting harder to burn GPUs. I have two left this year and may struggle to use before end of Jan 2015. It's hard to balance the cadence of usage too - you want to use them wisely but not get left with spares! I've missed 3 applications of GPU in the past month:
1. SFO - JFK p.s. (booked and applied GPUs for me and companion 3 weeks out with no R space but 10 biz seats open) 1st on list -24, 1 seat open, but no dice, lost to 'buy up' I guess.
2. EWR - NRT on W (booked and applied GPU for me 2 weeks out, no R space but 12 biz seats open) -24 showing space in biz, 2 seats, 2nd on list then lost out to a 'buy up' again I guess.
3. EWR - CDG sponsored non-member on Y (booked and applied GPU 3 days out, no R space and only 2 biz seats open) -24 no space in biz, 1st on list but no GPU clear.

My advice is to apply GPUs liberally on long flights whether domestic or international and to not wait to use. It is getting tougher to guarantee their clearance.

As an aside I am currently doing an AAA EXP challenge - with AA if you don't clear (which happened on a recent intercontinental flight) they recognize this and treat you really well in the economy cabin - free meals, movies, personal attention, etc.