Hi Will,
Today, there isn't much value in search engines besides the top 3, Google, Bing & Yahoo. There is really no difference in those 100 search engines to the top 3.
That being said, Google, Bing & Yahoo are all sophisticated enough to crawl and find your website without it being "submitted". It is a great idea to submit a sitemap for sure, but you dont need to submit it every week. If you follow the http://www.sitemaps.org/ guidelines you can set it up where the search engines will automatically revisit your sitemap and crawl your content on a daily, weekly, monthly, etc basis.
Also, If you are using WordPress you can download a free plugin to create your sitemap that makes it easy to set up the crawl basis.
I hope this helps.
Thanks,
Casey