I know this was a tragedy. I watched it via media starting immediately after. It was heart wrenching. Probably followed every article, movie, book etc on the day since. We were older, we knew. Why we chose 911 Memorial & Museum. We felt our guide was lovely, but miscalculated. Millenials & younger would have benefited more from the "Ground Zero" segment of this tour. We wanted to be "seeing" & exploring, not sitting & being talked to about events we'd so closely followed. We wasn't in New York at that time, but like all or most adult Americans then, our hearts & minds 100% were! (every minute of it). I'd suggest the guides find out if those buying the tour have a need for 911 education. At the very least, talk while showing sites at all times.
Meeting place: Although it was the church fence that became a Memorial, would have been nice to permit a quick tour of it as well. We were denied that upon asking. Would have paid any fees...
The Museum, Memorial & One World Observatory were self guided. This tour only supplied the admission tickets. Unless you somehow know nothing about "ground zero", I would recommend advance purchasing tickets to the 911 Museum & One World Observatory. The 911 Memorial is right together with those two & no tickets needed for it. This tour spends their entire time on ground zero, then hands you the tickets you could have bought yourself, and leaves! Again, the girl was lovely, the tour just isn't what we would have wanted.