Demographics: Generally, these people are already experts in some area of knowledge (medicine, law, public realtions, etc.) and they're looking for a way to boost their income by speaking for a fee.
Probably most of them already have spoken in public, but either for no fee or for an honouraria of $100 or so. My email newsletter will give them tips to start earning $2000 per speech — to begin with.
It will be a professional's site and newsletter — not spammy looking, not "make money now!" looking.
Also, as marketing your services as a speaker is largely about personal branding, I'd like my name in the logo design, even if quite small: Like "Tod Maffin's PROFESSIONAL SP...." etc. If you are able to work in a photo of me speaking, even better. My photos are at http://www.todmaffin.com
That said, "Professional Speaking Tips .com" should definitely be the focus of the logo design.
I'll need the design to work in (and be provided in) both vertical and horizontal alternatives for the most amount of flexibility.
The logo will appear primarily as a header on a Wordpress site and as a header on email newsletters. It may also appear as an introduction to a video.