I play a ton of guitar, so here goes...all sure-fire winners i've had requested from people who knew them...and more importantly, people who didn't request them actually recognized the songs without necessarily knowing the title or artist...
oasis- wonderwall That's gotta be the most requested 90's acoustic song by anyone.
live forever, or champagne supernova
dashboard confessionals- screming infidelities, a lot of other stuff...
spoon- underdog
van morrison - brown eyed girl, wild nights, lots of other stuff...
the rolling stones- jumping jack flash, you can't always get what you want, or street fighting man
pearl jam- elderly woman behind the counter in a small town, corduroy, daughter, or....
better man (that's also a top 90's request rivaling wonderwall)
stone temple pilots- creep, plush
led zepellin- stairway to heaven (obviously)
nirvana- all apologies, about a girl, lithium
crosby stills and nash -pretty much anything
the verve- lucky man
neil young- cinnamon girl, heart of gold, old man, hurricane, down by the river
the dandy warhols- bohemian like you, we used to be friends