Etiqutte for playing for friends, and other informal setting.

[etcetra]

My family asked me to play one of my composition for their family friend's wedding, and it got me thinking about this topic.  I don't have problem playing for my close friends but It seems awfully patronizing to play at a wedding for people you barely know... it can come across as a shameless self-promotion or showing off. 

I also think it would sound out of place.   I am playing jazz, but my piece tend to be more modern (post-bop), and I know its not the kind of music that is accesible to most people.. esp where I live, where there is little or no jazz.  I imagine it's just as awkward playing prokofiev sonata for a wedding.

How would you guys feel if your someone asked you to play something for a friend of a friend's wedding?  For me its like playing at an open mic at a coffeeshop.. It's done with the understanding that the participant is an amateur.. I guess you can play cocktail piano or 1st mvt of moonlight.. I guess it comes down to the fact that the performance won't be a dignifying experience at all.

[etcetra]

btw there is already a band playing for the wedding, I am asked to play couple of tunes.