Coming to America: What is the best legal structure for selling your products in the USA?

As an international lawyer, my clients based outside the U.S. often ask how they should structure sales of their products in the U.S. market.  Actually, they usually say, "we have decided to form a U.S. subsidiary [or to sign this proposed agreement, or to...], how much would you charge to help us?"  And then I ask some questions and the client and I work together to implement a strategy that meets the client's goals, which may be ...