Do you find it more interesting or less interesting when a band has diferrent lead vocalists on different songs? Every time someone writes a song in my band, they want to be the one to sing it, and I don't really know if its a good idea to switch vocalists so much. I sort of like the idea of variety, but it can sometimes be confusing, too.

I say switch vocalists. Variety.

Depends on the feel/mood of the song.

I think you should have one main person singing.

Chorus and stuff is alright for more than one person.

maybe once and a while someone else can sing

Yeah, take Alkaline Trio for instance. Matt Skiba writes most of the songs and is superb at what he does. Bassist Dan Andriano also writes equally great songs. However, Dan could not sing a Matt-written song, and vice versa, because the two vocal styles are completely different and require a different mood for the song to sound good.

Daron and Serj FTW

Multiple vocalists, depending if they actually can sing or not. Just listen to The Band, they do it beautifully. If the person who wrote it sings it, he's the only one who can really understand the song and try to convey the message behind it through his voice. He knows how it should sound.

Liam and Noel Gallagher of Oasis mix it up nicely.
Works for them.

KISS switches between Gene, Paul and I heard Ace sings some of the songs too...obviously successful, but not just because of the music.

At first I thought you meant multiple lead vocals in the same song, which would be...probably awful. Two lead guitarists can rock (Judas Priest!) but vocals are better with a lead and chorus. But for different songs, yeah, as long as they have good voices and can sing, go ahead. But if the vocals are the defining aspect of your music, it might sound like you have three or four different bands.

sikth and blood brothers pull off dual vocalists with ease.

go for the better route, sing like mike patton, he don't need no backing, he can do every style going.

*hates singers with the same voice on every song*

I prefer the idea of one frontman, but my drummer always wants to sing, so I'm in the same boat as you.

Then wy is he a drummer? It makes no sense!

Too many lead singers isn't a good thing, IMO, but if you find the right balance it can work quite nicely.

That's one of two reasons I'm looking for a new drummer. Right now, I occasionally let my drummer sing, just so I can play drums in his place.

Mine wants to sing while playing the drums. It makes the three of us in front look insanely stupid doing nothing but strumming our guitars.

Not really, I've seen other bands do it. The secret is to make sure your drummer can actually be seen.

Consider: Temple of the Dog. Two lead vocals.