I was wondering this in the beginning, but after going to 4 interviews (and 3 more to go), I have really observed a variety of options. In my opinion, it's best to have either one professional bag or portfolio. Coach (professional ONLY, not the ones with Cs all over them), Franklin-Covey (great choice, a little high though), or even Wilson all are great options. Trust me, you can squeeze all of your important items into a bag of this type. I also bought a cell phone holder that matches my portfolio. Maybe I'm being anal about this, but at my last interview there was a girl in a gray dress, black shoes, black portfolio, blue blouse, and a brown coach purse (with the Cs). There was just too much going on there. I say keep it simple and professional.