In fact Jack Cassidy was the first choice to play Ted Baxter and he was busy with something else.
They didn’t even try. Don and Ann were professional virgins in NYC at the height of the Sexual Revolution. Now that I’m older and wiser, I understand why Don was always so eager to go home to his own apartment after spending an evening at Ann’s place. He wanted to (as my daughter put it) “rub one out.”
Kind of puts a whole new slant on things, eh? 
I do give That Girl credit for “advancing the plot” and portraying that sort of young woman. Previously single women in sitcoms were typically more the man-hungry old maid type.
He & She, Jack Cassidy was allowed to play things more rakish than previous. Don’t really like Richard Benjamin much, his white bread Woody Allen bit hasn’t aged well. Not enough of an update, not that sorry He & She died. The Bob Newhart Show improved on the formula because Newhart was funnier than Benjamin and the psych angle was fresh for the times.
Cassidy wouldn’t have worked as Ted Baxter, would have taken the show in a different, less productive direction IMO. Too distracting.
Weren’t there a few episodes in MTM where Mary met “Mr. Right Now”?
Oddly enough, she was hot and heavy at one point with Ted “Don Hollinger” Bessel. IIRC, he lasted all of two episodes before going “out of town” and disappearing forever.
The oddest boyfriend was probably Jerry VanDyke.
She must have had an incredible sense of deja vu doing that episode.
He was also, according to Shirley Jones’ memoir, hung like a horse.
No wonder he was always so cocky! 
I guess the gist was that the men that were “in her league” wanted her to be a side piece instead of a working woman. This was set up in the pilot. The men that would accept her as she was typically weren’t in her league. Ah, the travails of a 10 woman.
I remember F Troop well. Corporal Agarn: “Who says I’m dumb?” was a frequent punchline. Great team of Storch and Forrest Tucker.
A thread about Larry Storch, who worked for years with Forrest Tucker, and Jack Cassidy gets the thread’s todger acknowledgment?
I’d swell with pride too if I were banging young Shirley Jones! 
After watching that video, I understand why my mother always referred to him as “Torrest Fucker.” I thought it was because she just didn’t like him, but now I know better.
I kid you not. She hated F Troop because it had so many “loud mouths.” She said the same thing about McHale’s Navy, which only made me love both shows even more.
She also hated Star Trek. Anything that irritated her, I loved automatically.
Just to continue the Jack Cassidy hijack:
Reading about He & She gave me a weird flashback, and I dove down the rabbit hole to try to exorcise it. Oscar North was cast to play his television character in a musical and went blank in mid-performance. We were then treated to seeing Jack Cassidy sitting on the edge of a stage singing “Somewhere Over the Rainbow”.
Am I finally losing it (not an unlikely possibility), or can someone confirm this?
There are episodes of the series on YouTube. I believe that’s one of them, since I seem to remember it too.
I searched YouTube and found a number of episodes but not that one (episode 17, “45 Midgets from Broadway”). But at least someone else remembers it.
I probably remember it from TV then. There were a couple of episodes that stuck in my mind, like the one where Benjamin hires Julie Sommars as his inker and she’s a complete klutz.
I remember this passage too:
CASSIDY: I just came from Washington. I had lunch with the President.
PRENTISS: My, that’s a great honor!
CASSIDY: Yes, but he deserved the privilege.
I think in the “Broadway” episode, Cassidy performed the Jet Man theme in full costume while in Benjamin’s office.