I once posted my favourite CSI episodes (long time ago). Now I'm going to do it again, but I can only pick one (maybe two) episodes each season. Here I go:
Season 1 - Boom
The episode where Nick has a one-night-stand and the girl gets killed. Catherine has to prove Nick's innocence. First Nick centric episode and a great one. The other storyline in this episode is the one with the explosion in the office building.
Season 2 - Stalker
Again this episode is centered around Nick. The team finds out that someone is stalking him. Especially the scene where the stalker is holding Nick at gunpoint is very strong.
Season 3 - The Accused is Entitled
My overall favourite. Chad Michael Murray guest stars as an actor held for a double murder. Big shot lawyers are trying to convince the team that he's not guilty and they are throwing with dirt. They bring up personal stuff to break the team down and make sure their client goes out free. Wonderfull episode.
Season 4 - Suckers
That episode where Warrick and Catherine have to mingle in the world of vampires. Creepy and disturbing in one way, but it's a very exciting storyline. The other case is with the Samurai sword that goes missing.
Season 5 - Grave Danger + 4 X 4
I had to choose two. Grave Danger is the obvious choice. I think it's the most popular episode for CSI fans. And it is a great epi. The team works together in a race against time to find Nick. And Quentin Tarentino directed it, which made it even better. The other episode really stood out that season. Four different cases and each story took place at the same time. So they literaly had two rewind the episode sometimes. Great way to film an episode.
Season 6 - Gum Drops
Nick has to lead a case where a family is killed. They just have to find the young girl Cassie. I like Nick as a leader and the end scene is very memorable.
Season 7 - Toe Tags
Four different cases and the episode is seen from the victims point of view. Which is a whole new twist. I especially liked the storyline with the war veteran.
Season 8 - Lying Down with Dogs
One of the most horrifying cases. Not the woman getting killed, but what that woman did. She 'created' fightdogs. That's awfull. The first time that I could actually understand the murderer and why he killed. And also the first time that I didn't feel sorry for the victim.
Season 9 - Turn, Turn, Turn
Wonderfull episode, with Nick as a leading character. We see three different cases in a motel, that happened all in one year. Haley (guest star Taylor Swift) is the constant factor in all stories. She even ends up dead herself. It's a sad story, but a very strong one. Wonderfull epi.
For season 10... we'll have to wait a little.