Yes, let's memorialize the 3,000 or so Americans (and others) who died in the attacks of 9/11, but only if we also remember the 4343 American soldiers who died in the course of waging a wholly unnecessary and ill-conceived war in the wake of 9/11. And, of course the roughly 100,000 Iraqi civilians who have died in the course of that war.
I'm trying to refrain from political thinking today, in the hope that that will be the best way to honor the dead. The vast majority of the dead indivduals above probably weren't that interested in politics, religion, or war, and just wanted to live their lives. But as Trotsky said, "You may not be interested in war, but war is interested in you." Choosing sides is always necessary; the best we can do is be on the side that is against conflict.