I actually like that Garak survived because his character was arguably one of the most complex: You have no idea what he's thinking but you sort of get a feeling that, over the course of the series, he develops his equivalent of a conscience. Seeing him quietly crushed at the utter devastation of his home world was an interesting place to see him leave off. I know that his actor, Andrew J. Robinson, would use an old acting technique and write a diary from Garak's point of view to help him figure out motivations. To help him get closure with the role, after the series wrapped, he added some more entries, this time as supposed correspondence with Bashir, and with the blessing of Paramount and published it as "
A Stitch In Time". I have a copy but haven't read it--the consensus is it's supposed to be very good for what it is as Robinson understands the character so fully that it really
does seem like something he would write.
I also liked the all-Vic Fontaine episodes and that they somehow (1) got a real singer from that era to play the role and (2) made the character work. I also liked how Sisko sniped about how, though the holodeck fixed it, black people weren't welcome in that age.
The end for Sisko was originally scripted and filmed as much more final: He's not coming back. Apparently, in the 11th hour, Brooks called the producers and asked if they could make there a window to his possible return only because he felt weird about portraying another black father not being there for his family. They then went back and refilmed his talk with Kasidy Yates to have some more ambiguity. It's kind of brutal that he never says anything to Jake--which makes that last shot of him looking out the window more sad but appropriate for the episode's theme and title "what you leave behind".
There was a long-running plan to give the last line of the entire series to Morn (who had the same actor throughout), but they instead went with Quark--and the line "the more things change, the more they stay the same" was great.
The stuff with Dukat and Ziyal was my favorite part of Dukat: the way he loses his sanity immediately after her death was crushing--you could tell that any chance of his character redeeming itself died with her.
I liked that Damar's death was abrupt and didn't allow for some great final speech--brutal and realistic. Interestingly the Cardie who had replaced him as the Dominion crony was the same actor as the Mars cab driver "Vinnie" from Total Recall.
With that said, characters like Garak and Damar were examples of how the writers were willing to take what were initially minor roles and run with them when the actors seemed to show promise. On the flip side, Bareil (the Vedek Kira was into) wasn't working so great so they eventually wrote him out.
As for the montage in the final episode, it's too bad Terry Farrell's agents were unable to negotiate her clip appearances--that's why Jadzia never appears and they only show clips with Erzi. That scene in the holodeck, with everyone drinking at Vic's, actually has most of the cast, crew and others without make-up in the background.