It’s a bummer, but AE doesn’t have the ability to have two different fonts in one text layer through expressions, yet. If you’re trying to keep “layers” to a minimum and not necessarily compositions, you could do what Chris suggests. Create a Comp that has the names in the style you want, use an expression to read the comp name and split it up, then just duplicate that comp for as many of the names as you want.
It’s not exactly what you want, but it’s a work around until that functionality is available. I’m sure there are other ways, too.