NBC (ended 2004)
I also have lots of favorites. Some of them have already been mentioned above, such as Daphne's Room and also The Innkeepers, which was hilarious, especially Niles and Daphne with the eels and towards the end when the cherries jubilee exploded, with Roz coming into the kitchen covered in cherries and her hair standing straight up.
David Hyde Pierce's performance in Three Valentines was nothing less than brilliant! Another couple of episodes where the comedic genius of DHP shone through were An Affair to Forget, where he had a duel with Maris' Bavarian fencing instructor, and also his little breakdown in Murder Most Maris, in the final season, where he stripped down naked in Cafe Nervosa due to the stress of Maris' incessant calls to him from jail.
Room Service was another great episode, not only because of the obvious humor, but also the unexpected plot. Niles and Lilith's one-night dalliance came as a total surprise.....they were a most unlikely duo!
Lastly, I liked all the episodes which included Kate Costas (Mercedes Ruehl) in the third season. I thought her chemistry with Frasier was second to none, and the two of them did comedy so well. I've always said it's too bad she didn't come later in the series, as I think she should have been the one with Frasier in the end.....not Charlotte (ugh!).