Davis Rules, on ABC (s1) / CBS (s2)
Carsey-Werner; IMDb; Retro Junk; Sitcoms Online; TV Tango; Wikipedia

This was originally on ABC, in 1991, so I didn't get to see the first season, because I didn't get ABC, back then. The second season was on CBS, so I did watch that. I'm afraid I don't really remember anything about it except some of the people who were in it, and the fact that I liked it. And I remember the theme music. Anyway, it starred Randy Quaid as Dwight Davis, who Wikipedia reminds me was a widowed high school principal, raising three sons with help from his somewhat odd father, Gunny (Jonathan Winters). Aside from them, I also remember Bonnie Hunt and Giovanni Ribisi in the cast, but they were added in the second season (which, as I mentioned, was the only season I've seen). Hunt played Gwen Davis, Dwight's sister. And Ribisi played a guy named Skinner, who I think was like a neighbor or something (he would have been like 18 at the time, and I think this was the first thing I ever saw him in). I remember liking the whole cast and finding the show funny and quirky. I wish I could see it again, so I could write a proper review. And, you know, enjoy watching it.

Oh, and here's some theme music for you.