Under those guidelines, I'd say...
9 to 5
All of Me
Bowfinger
George of the Jungle
Modern Times
My Cousin Vinnie
National Lampoon's Christmas Vacation
Roxanne
School of Rock
Twins
Not available on Lovefilm, I ask that you consider Brain Donors, a modern day Marx Bros. movie with John Turturro doing a really great Groucho. It's not great by any means, but it's really funny and a brief 75min.
BRAIN DONORS: Movie Trailer