I would have to agree with keeping it small. Have 5-10 total pieces and a couple good case studies. It also helps to state though that you can provide additional pieces to potential clients wanting to see something related to their business. A lot of times a list of clients helps convey that you've done a lot more than what's shown.
Keep taking the small projects because those are typically the ones that fill in the money gaps between the big projects. Then just show your best work.