Unfortunately I couldn't embed the Gilligan themes, but there are links there.
Gilligan's Island (1964) -- The ORIGINAL opening from the unseen pilot episode
Gilligan's Island (1964-1965) -- first season
Gilligan's Island (1965-1967) -- intro with Professor and Mary Ann
Gilligan's Island (1964-1967) closing theme
It's About Time (1966-1967)
The Brady Bunch (1969-1974)
Dusty's Trail (1973-1974)
The Brady Kids (1972-1974) -- did every popular show in the era have a nonsensical animated counterpart??
Big John, Little John (1976)
The Brady Brides (1981) -- short-lived series spun off from a TV movie
The Bradys (1990) -- ill-fated one-hour drama version of everyone's favorite blended family
And the less said about The Brady Bunch Variety Hour the better.