Was i the only one reminded of the play/movie Noises Off while watching the scene in the cabin with all the doors? I really enjoyed that portion of the episode, purporting the free flowing absurdity that makes this series so great to watch.
Basically, Niles hires Saul Rubinek (playing "Donny") to be his lawyer, who finally ends his divorce preceedings with Maris. Of course as soon as it's over Niles finds Donny dating Daphne, the irony and sadness of which is pointed out to him rather imemdiately. He invites Roz to his newly re-acquired lake house with the intent of getting Donny to reuinite with her now that she finaly has a kid, the lack of which that broke them up previously and Roz went along willingly.
Suffice to say the ensuing zanyness to get Frasier and Martin to not notice this going on, or their presence even was highly hilarious, drawing from a Noises Off type premise, and i enjoyed it immensly, all winding back to Niles once again brooding under the piano at Frasiers place.