The Brady Bunch theme does exactly what it sets out to do, and 40 years later, EVERYBODY knows it, even those who didn’t like the show.
Same could also be said for The Beverly Hillbillies.
No one mentioned Get Smart?! Rated #2 all time by TV Guide.
As a kid, I loved the short lived Logan’s Run theme, complete with Blaster Gun sound effects.
British Danger Man theme (”Highwire”), but also American “Secret Agent Man”.
I would also put in a plug for Crime Story featuring the great Del Shannon.
For obscurities, I would go with The Practice with Danny Thomas (Season 1) and Grady.
I repeat recommendations for Peter Gunn, The Prisoner, Perry Mason (love the piano playing behind those soaring horns), Rocky and Bullwinkle shows (Bullwinkle version). Spiderman theme also should get cartoon recognition.
Nothing wrong with The Munsters theme, either.
Not an American television show, but the theme to All Creatures Great and Small (based on the wonderful books by James Herriott) was fun.