I remember watching this show as a child. I liked it well enough that I still remember it over fifty years later. I was talking about it the other day with someone who also remembered it as being wholesome entertainment for her children that she and her husband enjoyed as well.
The thing I remember best about it was the relationship between the Whiting sisters, which was very believable to someone my age. Some of the plots were a little far fetched but I got so caught up in them that I believed they were possible. But the relationships were the thing that has stuck with me all these years. The show was clever and not laboriously "funny" as most of our modern sitcoms are; they were sisters and they got into sisterly situations which they then worked out satisfactorily.
Even at a young age I was a fan of Margaret Whiting's music as I still am. I suspect at a remove that that fanship was the underlying reason I was such a big fan of the show. Both of the Whitings were attractive women but Margaret had a certain glamor that Barbara, being younger, lacked. The difference a few years made in them was a large part of the continuing plot. It was a good, entertaining show but its storyline had a finite lifespan as the older Barbara became the fewer differences there would be to play on. Both Whitings were talented though Margaret was a better singer than actress. The show also had a good supporting cast.