I think maybe the ukulele could be underestimated.

Misirlou (cover) - Pulp Fiction Theme - Ukulele Death Squad

Not Afraid - Ukulele Death Squad

Scroll down to the video of this song: Into My Arms

or scroll down to this one:

All I Want is You

or check out some of the other videos on their website.

I went to the Newcastle (i.e. NSW, Oz) Ukulele Festival last year and saw a lot of brilliant performers and groups. The uke was used for lead ins and melody lines a lot.

If it's just an all in session with lots of other types of instruments then the uke would fight to be heard but if it is a specific agreement e.g. for the uke to play the lead in or the break in the melody or something, then it would work.