I have a Thursday night beer and boardgames group that occasionally dabbles in rpg games, and the irregular Marvel Super Heroes game I run has actually been more common than my supposedly bi-weekly Dungeon Crawl Classics game.
The group started as the Northeast Florida Avengers, based out of Jacksonville, the town we live in. Half the fun is letting the players role-play inconsequential stuff between themselves. They are based out of an office at a strip mall on a highway, they drive a Volvo to adventures and started off as generally ineffective. Over time they've developed their powers in play (thanks to the ingenious Power Stunt system and my lax enforcement of Karma expenditures for stunts), defeated the corrupt Tallahassee Avengers, and managed to overcome anything I've thrown at them.
They defeated a demigod from Atlantis and stole his magic trident.
They defeated hypnotized heroes and a giant robot controlled by The Hisser.
They defeated an alternate reality Sinister Six with the help of Thor.
They defeated the Hisser and the rest of the Tallahassee Avengers when they summoned the Dread Dormammu.
In the most recent session they travelled into space and explored a shattered asteroid prison, known to the resident alien on the team, Starbucks Jones from the Andromeda system. I used this amazing one page dungeon to great success. I've tried to tie sessions to particular characters. In the alternate reality where the Sinister Six had taken over Jacksonville, the team's powered armor hero The Shack was that reality's Spiderman. When Dormammu was summoned, frat-boy turned native american spirit champion The Seminole had visions of warning (though he barely understood them because he doesn't speak the language).
Humor has been a huge part of the game. Everybody is ridiculous. Rex Powercolt is a superstrong shapeshifting mutant that is dumb as a bag of hammers and tries to mate with alpacas. Dr Mighty Mirror buys billboards around town to promote himself (slogan: "You've heard of me"). El Capitan is the only conquistador who found the Fountain of Youth, but hundreds of years later he's an old man in sweats who forgets things. The Shack has slowly been upgrading the team vehicle, so now they have a volvo that can fly in space (and has heated seats).
They've come a long way even though we don't play that regularly. I'm very forgiving with power stunts to expand their powers and I let them raise ranks somewhat arbitrarily. Their name changes to reflect their growth as well. Recently they parked the remains of the interstellar prison asteroid on the lunar surface so they can call themselves the Dark Side of the Moon's Mightiest Heroes. Assuming Black Bolt of the Inhumans doesn't say otherwise. ;)