This was on TV Guide.Com on a Q&A Feature called Televisionary:

Question: Okay, my friend and I have a bet. She thinks Three's Company was based in Los Angeles and I believe the setting was definitely Santa Barbara. Which one of us is right? — Catherine Brown

Televisionary: Technically speaking, you're both — how do I say this? — well... wrong.

Janet Wood (Joyce DeWitt) and Chrissy Snow (Suzanne Somers) were looking for a roommate to share the rent in their Santa Monica apartment when they discovered Jack Tripper (John Ritter) snoozing in their bathtub following a party. (Santa Monica is in Los Angeles County so maybe your pal can insist that's what she meant if she's that shameless; on the other hand you can retaliate by saying any Santa is close enough.) Facing a problem that seems almost quaint by today's standards, the three snuck Jack onto the lease because grumpy landlord Stanley Roper (Norman Fell) mistakenly believed he was gay and would never be interested in female roommates... that way.

It's tough to figure out which element is more unbelievable: that coed roommates would be forced to concoct such a tale in order to live together or that a network could get away with the offensive limp-wrist humor that ran throughout the series.

Even more incredible is how long the show, based on the British comedy Man of the House, lasted given its lame gags and numerous cast changes. During its 1977-'84 run on ABC, it survived the departure of Somers, who was replaced by cousin Cindy (Jennilee Harrison) and then new roomie Terri Alden (Priscilla Barnes) as well as the exodus of Roper and wife (Audra Lindley), who left to launch a spinoff.

Chalk it up to the power of TV titan Don Knotts, who came on as ascot-wearing landlord Ralph Furley (cue the bug-eyed double-take).

Now, can I ask y'all something? Why did the show get it's best ratings without Don? Weird!

Okay, I would agree with the above column, because it did have alot of the same kinds of jokes, and the one thing also that may be bad about tc is that it always had jack potraying a gay person. This today would be kind of homophobic, and it is probably offensive to gay men out there. That is one thing I dont like tc for. I think that sux hard for them. But what does ev body else think?

By the way i think the t.visionary meant that when s.sommers left, the show would've been surely sunk, and it would've been taken off alot earlier than 84. Rf I think did save them.