I'm going to open it up a smidge and run with "upbeat" movies, some of which are obvious LOL comedies, others which leave you on an high note, but may not be belly-laughers. A lot of these are classics my mom introduced me to as a kid.
The Blind Side
Speed
Searching for Bobby Fischer
Rumble in the Bronx
Big Trouble in Little China
Some Like It Hot
The Odd Couple
O Brother Where Art Thou
The Quiet Man
Rooster Cogburn
Operation Petticoat
Father Goose
To Have and Have Not
The African Queen
The Pink Panther
Mr Smith Goes To Washington
How To Train Your Dragon
Despicable Me
The Incredibles
Cars
Groundhog Day
Spies Like Us
Ghostbusters
Finding Nemo
The Lady and the Tramp
The Fox and the Hound
Ed Wood
Plan 9 From OUter SPace
The Princess Bride
Butch Cassidy and th Sundance Kid
Casablanca
Forrest Gump
Blast from the Past
The Mummy (Brendan Frasier)
Amazing Grace
Rocky
Napoleon Dynamite
This Is Spinal Tap
Time Bandits
Austin Powers
My Big Fat Greek Wedding
Ferris BUellers Day off
Uncle Buck
Airplane
Scary Movie
Evil Dead 2
Army of Darkness
Shaun of the Dead
OK, that's all I can think of, for now.
Looking back, I can kinda see my thought process. Like a spastic Jack Russell Terrier determined to be upbeat. It sort of makes sense, except for The Mummy>>Amazing Grace. That one, I can;t explain.