I stopped watching the original when Warrick died. (I don't even think I finished watching that story-line. All I saw was him get shot and I quit watching.) I stopped watching CSI: Miami when I finally realized that they were never going to let Calleigh and Jake be together, which happened sometime during season five...or early six, I wanna say. (I also didn't like the changes they made in Horatio's character and his dynamic with Calleigh; they barely said two words to each other in what I saw of season six when, at the beginning, they used to work every case together.) And I stopped following the goings on of CSI: New York when Danny and Lindsay got together - I'd been rooting for Lindsay/Flack, you see.
To be honest, though, I never really watched CSI: NY on a regular basis after Aiden died and I know for sure that, even if Lindsay and Danny hadn't gotten together, I wouldn't be watching now that Bonasera is gone.