Ok, this is what I'm trying to do. I'm in a trio (guitarist, bassist, and drummer). I want to be able to record all of us together, but also record just myself (vocals and guitar) in my bedroom. I ALSO want to be able to record us together in a LIVE setting. I know I may be asking for a lot, but I can't find a Interface that meets all my needs.
for drums, guitar and bass you'll need more than 3 inputs anyway,

Kick drum,
Overhead Left
Overhead Right

Bass cab

Guitar Cab

Vocal mic(?)

you'd do well with an 8 channel interface.

also, i'm sure that interfaces usually have numbers of inputs that are multiples of 2, i suppose its designed as multiple pairs of mono channels in most cases.