Mark, since you've indicated you're swamped with suggestions already I won't make you crazy by adding more suggestions. But I do want to chime in about Dr. Lathe. Neil made a neck knife for me recently and I posted a brief description of it about a month ago. It's a beautiful piece of work that came with two sheaths, one for neck and one for ordinary carry. Mine is talonite and it's absolutely amazing. It might be a little heavy for some to carry around the neck, but I understand that Mr. Blackwood will make up a similar one in a lighter metal. Check it out.
If you are set on an Americanized tanto shape, the Gerber Nealy is pretty. If you want a special treat, look at the real, custom Nealy's. Probably the most versatile sheath system around and superb flat, light knives.
