At 8, WORLD TRADE CENTER came on Showtime-HD, and we watched that. It was an involving movie, but I didn't find it nearly as harrowing or as moving as UNITED 93.
It basically focuses one two Port Authority policemen who were trapped when the towers came down. Then there are lots of flashbacks to show us each man's family life. Was surprised to see Donna Murphy in a small part.
The HD version was beautiful. Of course, in the "present" scenes trapped under the rubble, all the dark and gloom isn't made any sharper in HD, but all the flashback stuff and the early morning scenes ebfore the planes hit were just stunning.