I don't think there's such a thing as an "ideal" size - it just depends on your design, what looks best with it (ie thick, thin, circles, etc). Once I had a design that didn't look right with thin chain but all I had was 1mm sterling curb... So I cut each length between the bead components 6 times to make it thick! Looked great but what a pain getting all those little tiny chains cut the exact same size! LOL
It also depends on how you're connecting components - if you're say, using a jumpring that won't go thru the chain link, then no matter how good it looks, you have to redesign it somehow.
Good luck hunting and have fun!
Angela