Well just to name one, I think 389 has them all in, though it's mainly Sanji and Luffy. Thing is, it's not going to really work off one episode since the characters have different sides shown in different episodes. The bit when Luffy and Usopp argue and Usopp then leaves the crew happens in 235 and you see a side of Usopp and Luffy you haven't really seen up until that point. Again, Robin when she's with CP9 acts differently from when she's with the Straw Hats. And so on...
You can see all the episodes and their titles on
Wikipedia - the titles should give you clue as you who will be in the episode, since you've read the manga.