Here is a short list of some favorite episodes;
The Parking Garage. This episode is a prime example of the "Show About Nothing" metaphor got started.
The Chineese Rstaurant. Like the above episode this one was real and it contains Elaine's hilarious speach about eating out.
Bizarro Jerry. This was a prime example of how it was possib;e for the new style Seinfeld could be funny.
The Trip. This two parter has Kramer split to the coast.
I don't remember the title but I liked the one where Elaine has a 66 year old boyfriend.
The Red Dot. Elaine gets George a job at her Publishing house. He gets firewd after making love to the cleaning lady.
The Maid. This late episode was one of the few from the last season that didn't suck!!!
The episode with "Jimmy" in it. And notice how many times George talked in the 3rd person after it aired?