If you care about your work, and respect your creative team, always present initial creative concepts in person. This gives you the opportunity to “feel their reaction.” If the work is rejected, you will understand what the issues are and how best to address them.
Remember, the client is not just asking for a piece of paper with an idea on it, or a PSD of the web site home page. They re looking for your insight and rationale: HOW you chose the graphics/words, and understanding WHY you undertook this approach. Even the best concept, well researched and developed, can be destroyed by a misconception on presentation or a concern expressed by a senior client that is not properly addressed on presentation. Don’t count on a junior or intermediate level client to effectively present your creative concepts up the line. This is a hit or miss proposition.