Need new shoes - recommendations?

I've been using the exact same make and model of shoes for almost everything I do, which mostly involves walking. And working out. But I'm tired of using walking shoes for my workouts, as I don't think they're ideal. They work, but might not be the best. Or does it matter?

I've looked at cross trainers before, but they all have leather, and I'm vegetarian for ethical reasons. I don't want to use shoes that are leather, and I haven't found cross trainers that aren't leather. Does anyone know of a "vegetarian" cross trainer brand I could look for?