I don't think that they could fairly pick The Best CSI episodes, all of them would be biased in some way. Depending on what you like, for example, your favourite character, whether you like more science or more drama or more emotional cases, etc. It's going to be biased either way. No matter what they do.
I'm not a huge Nick Fan, but I still think Grave Danger should be on there, but probably since it's a two-part episode, they decided not to show it.
My favourite character is Sara, so I think that Nesting Dolls, Committed, Homebodies and Bloodlines should definately be on there.
But that's just me.
It would be better if they said something like 'Most Emotional Episodes of CSI' and then did another marathon for 'Most Outrageous CSI Episodes' or whatever other criteria they decide to use. The best episodes are different to everyone, so who is to say what the best ones are?