Hi David,
If you have a good structure on your website then there is no need for a HTML sitemap. By good structure I mean, is every important page on your site easily accessible within 2 clicks from any other page on your website? Are your menu's SEO friendly? Are your main products/services highlighted on your home page in summary? I do not use an HTML sitemap on any of my sites, I just make sure that Google can access every page that is important to me no matter where they land on my site.