I think such a commemorative of the "event" by itself would be unsavoury, but perhaps commemorating the heroes of that day would in itself be a fitting tribute for all that lost their lives that day. Heroes range from the frightened but cool and collective flight attendants on those hijacked aircraft calling their call centres, to the rescuers saving lives in the aftermath of the disaster. There were so many wide ranging instances of the best of humanity on that day that were overshadowed by the vile and hateful act of a few individuals. The former is what should be remembered and commemorated.