I need to purchase about 4.5K worth of tickets for an upcoming family vacation. I was just planning on using Citi Advantage Platinum card for 2X points. But after reading around Flyertalk, I am thinking there may be better ways to do this. Things that come to mind are the AA shopping portal to purchase gift cards, Costco, etc... Any recommendations on how to maximize, or is a straight Citi Advantage purchase the way to go? Thanks!