Just bought our first ever AP vouchers. We have a trip booked in full for April 23rd to May 1st. We have another trip partially booked (we have a week-long reservation booked with Hilton HHonors points in DTD for November so we can see the holiday decorations). We know we'll go again either February break or April break in 2016. Therefore, for us, 3 trips in a calendar year or less it only made sense,.
I also bought gift cards at Sam's Club to pay for the APs with. Helped to save almost exactly $100. The CM on the phone was super helpful redeeming them to cover the cost, it took 41 gift cards! He said his long standing record was 50+, but he had just done an 80+ gift card transaction a few weeks ago!