I think the title is pretty self-explanatory. What's the biggest band you've ever played in?
 
I ask because I am suddenly finding myself in a 9-piece:
drums, 2 guitars, bass, lead vocals, 2 female backup vocalists, 2 alternate female backup vocalists, and we're in the process of integrating a horn section!
 
big bands may be a pain in the arse to coordinate, but jeez are they fun!

7

Nine piece:  guitar, bass, drums, keys, multi (guitar/lap steel/fiddle), congas, 3 female vocals.  Big fun, but a bit crowed on some of the smaller bar stages.
 
Bill, tgo

Seven, not couting my Lab Band in High School.
 
OO

Most of my bands were 4 piece (guitar, bass, drums,vocal).  I played in 2 bands that had 2 guitarist and one that had a keyboard player.  Nobody could sing in any of them!!!  Now that I'm just jacking around in my studio, I'm suddenly running into a bunch of really good singers.  Go figure.

The band I play in, Moodswings, has 25.  That's six vocalists, four saxes, four trombones, four trumpets, two soundmen, bass, guitar, keyboard, vibes, and drums.  We're all together at the bottom of this page (new window).
 
As Robin says, they're a lot of fun.  On the down side, pretty much anything split 25 ways comes out to gas money.  And it seems like, with that many, there's always a personality conflict somewhere.

I guess if you count my Church group the number would be, 21.
7 female vocals
3 Male vocals
2 Keysboard/singers
1 Bass, yours truely
1 Drummer
2 Percusionist
2 Guitars
3 Horns
 
Irony of it is, the best bands I've ever played with were smaller bands,  
3 piece instrument, ICE ,bass-guitar-drums and a female vocalist
4 piece instrument BIG LUCY bass-2 guitars-drums
 
OO

played in a 20 or so piece jazz orchestra for a bit until i was replaced by a real bass player (upright guy).
 
everything else vared from 3-6 people.
 
the best? 3 piece singer songwriter ouitfit.  female vocalist, me, and an acoustic guitar player.

The most fun has always been playing 3-piece, especially P.O.W.s back in the mid-'80s in Nashville.  I've also played in a couple of ~75-piece orchestras..
 
John

A band I'm in, Local Disturbance, has 4, sometimes 5 players. But sometimes others are encouraged to sit in, typically on percussion or horns, and at one point we had 14 people on stage helping us. OY!

hmm, I wasn't thinking of classical groups when I started this thread, but John's post jogged my memory. The absolute biggest performance I've ever been a part of was a ~120 person symphony and 200+ choir.

Trouble about being in a large band is when you buy the round of drinks!!!...there goes your gig money!