Maybe I have a one-track mind, but Lee Grant's incredibly hot murderess Leslie, and Arlene Martel's incredibly hot comical character Gloria.

I think I've mentioned before in other threads, but I'm a huge Kay Freestone fan, in the sense that she showed many sides of emotion, and the character was played so well by Trish Vandevere. I do acknowledge, however, that her character had a weak reason for murder, relatively speaking.

For me, Blythe Danner's Janice Benedict comes across as a very compelling character, more sympathetic as a victim of Alex's deviant ways than the actual murder victim.
Throughout the episode she seems to struggle to have faith in her husband, while also trying to get at the truth, visibly and audibly dreading, it seems, what she'll actually find out. Her annoyance at Columbo in certain scenes seems more a fear that this policeman will confirm her suspicions than a distaste for the lieutenant's manner.
Of course, when Columbo finally does expose Alex, the strength of Danner's performance increases the intensity of emotion within the Janice character to an even greater degree.
Indeed, if I'm remembering correctly, she is the only other character in the series, besides Elizabeth Van Wyck in "Playback", that was ever shown weeping (though Ruth Lytton seems to come close at the end of "Old Fashioned Murder").
Elizabeth Van Wyck would actually be my second choice as the most interesting woman in the series, and of course she is quite similar to Janice, though is obviously completely trusting of her husband, which in a sense makes her character even more indelibly tragic at the end.

I think the wife in "Candidate for Crime" had tears in her eyes at the end.

I agree, Janice Benedict was interesting, and well performed by Blythe Danner. One scene that always kind of annoyed me though, is when she asks Alex why he married her as she wasn't talented, etc. - to which I always think, isn't it obvious?? Your mother has loads of money and the symphony connection, duh??? It always made me think that her character was a little naïve.

What's "relatively speaking"? Columbo made it clear that the murderer in the case would have a very good motive and we probably shouldn't doubt it, even if the episode didn't express it as well as it perhaps could have. But that depends on what you think the motive is.

Relatively speaking, meaning relative to many of the other motives in Columbo episodes, and meaning that there should be no "good" motive to murder as it shouldn't be an option one would think of. Kay Freestone's motive is rejection whether it be relationship rejection, or professional rejection and rejection is something that happens to people every day and it doesn't typically drive people to murder. Whereas someone like Abigail Mitchell, for example, was motivated to punish for what she thought was an unpunished murderer, and that's a different type of motive entirely.

Grace Wheeler!

Relatively speaking also in terms that Columbo was allowing for that fact when he used the term `good`. In actually he was making a distinction (probably slightly ironically) between the `motive` (that which drives and MOTIVATES the action) and the `reason` (which will never be good).

Also saying the motive is rejection is a bit empty because it can actually mean a lot of different things. In this case we know from the episode Kay's primary motive for just about anything was ambition, it's kind of why she got up in the morning. We also know that her relationship with Mark McAndrews was more like a business arrangement. Rejection wasn't the problem when he said he was leaving that did bother him, she wasn't bothered about not being taken with him. Rejection in those terms wasn't the reason. No, the reason and the motive was that he didn't give her the job which to her she'd worked for and earned and than tried to palm her off with a material compensation which wasn't at all what she wanted. To her her basically broke a contract doing that. In her head she was pretty insulted. It's hard to put it into words because it just boils down to saying she was really, really angry which is hard to entirely convey if you don't share her feelings.
But nevertheless the motive did seem to be anger and good old-fashioned revenge.

I just watched "A bird in the hand" and Tyne Daly's character Dolores was really interesting. Her exit at the end is one of the funniest bits in the whole series.

And earlier in the show, the scene where she refuses to give Greg Evigan the money is really excellent. Her character suddenly became a lot deeper than she appeared at first. I remember being surprised the first time I saw it.

Mrs. Columbo

Kim Cattrall in "How to Dial a Murder" ... At least, she was the hottie I wanted to spend some real time with.

From the perspective of me being a hornball, the #1 choice is Gretchen Corbett, in the bikini, in "Exercise in Fatality".

The most interesting killer is Ruth Gordon in "Try and Catch me".