It's hard for me to choose a favorite episode where the girls work together - mainly because they're so few & far between, that it's refreshing to see each time. Let me refresh my memory on C/S episodes:
The first one is Caged, then Snuff.
Along comes LHB where they don't work together, but they have great scenes together. As much as I love Catherine here, I always feel so sorry for Sara in having to work Eddie's case, knowing it's not going to end up the way it needs to.
Not to long after that, it's refreshing to see Sara as the conflicted one in Crash & Burn, where we finally see Cath's understanding.
AFOC - Ah! The bloated floater in the tub!! "It's raining man juice" - "hallelujah?" A Classic!!
Nesting Dolls - A decent episode, but I don't like all of the angst between the girls.
Up to season 6 - Secrets & Flies: This one I really like, especially when they were talking to the Project Sunflower lady. Cath starts getting confrontational, Sara is the one to calm things down. Such a nice reversal in their roles.
Fast forward to the end of season 7 - TG,TB & TD: Finally the girls working a scene together, but it was such a short time.
So, which are my favorites (based solely on Cath/Sara scenes)? -----
Let's go this way:
1. AFOC
2. Crash & Burn
3. Secrets & Flies
4. Caged
5. Snuff
6. LHB
7. TG,TB & TD
8. Nesting Dolls