Would you all agree that Petticoat Junction at the end of it's run in 1970 is a completely different series from the program that premiered in 1963?
I for one would. And it's not just about the absence of Kate and Charley(both actors who played the roles had died), but the focus is entirely different.
The early years,especially seasons two and three focused mostly on slapstick comedy. Some of it was quite cartoonish like Mr. Bedloe trying to outrun the speeding train in episode 2 of the series. Or just about ANYTIME that Betty Jo would drive the Cannonball, as the train would (usually, but not always) go at WARP SPEED whenever she was at the throttle!
As the series wore on the tone changed drastically: although there had been SOME singing in the early shows, mostly brief solos by Pat Woodell, the real "singing era' began in season 4 with the addition of Mike Minor as Steve and Meredith MacRae as the third Billie Jo.
Slapstick comedy took a back seat and the series began to focus MUCH more of singing and musical performances, and there was a LOT less physical comedy.
One more note about singing on the series, I personally consider "The Ladybugs" episode from season 1 to be in a completely separate universe from the true singing era from seasons 4 thru 7, because those musical numbers were done slapstick and played chieflyfor laughs.
The musical performance from seasons 4 thru 7 were done mostly straight, and THAT'S when singing became a big part of the series.
So would you all agree with me in the drastic changes in tone that PJ endured over it's 7 year run?

Only having recently seen the B&W episodes thanks to the DVDs, I can say that the early shows possessed a more rustic charm and due to the fact they were filmed in B&W and had many old-time character actors, to me they exude a 1930s-40s film era vibe like "Ma & Pa Kettle" etc. The early shows just seemed 'warmer' to me, if that makes sense. They had more heart.

When they switched to color, I felt it became more cartoonish (the same thing happened on 'Bewitched') and by Season 5 when Bea began missing shows the magic was definitely gone. It became pretty boring by the June Lockhart years.

Only having recently seen the B&W episodes thanks to the DVDs, I can say that the early shows possessed a more rustic charm and due to the fact they were filmed in B&W and had many old-time character actors, to me they exude a 1930s-40s film era vibe like "Ma & Pa Kettle" etc. The early shows just seemed 'warmer' to me, if that makes sense. They had more heart.

When they switched to color, I felt it became more cartoonish (the same thing happened on 'Bewitched') and by Season 5 when Bea began missing shows the magic was definitely gone. It became pretty boring by the June Lockhart years.

I pretty much agree, with Petticoat Junction there are two eras. Seasons 1 to 4, then 5 to 7.

I Dream Of Jeannie is the same way, the black and white season is completely different from the color seasons. The show got cartoonish when it changed to color, it's like they went crazy with the switch to color, I guess it's just what was happening at the time. 1966-67 is around the time a lot of B & W shows changed to color.

I actually think "Jeannie" became a better show when it got so wild and frantic. Season 4 is my favorite because of all the psychadelic colors and costumes and storylines they featured around that time. It just all seemed very well-suited to the show and vice versa.