.com taken, is .net, .org, .co worth it......................?

You definitely want to have a .com for your TLD. For SEO though you can create satellite sites with .net, .co, .org extensions to build content into your main site. You don't necessarily need to get an exact phrase match for your company like "LosAngelesDoctors.com" - instead go with the actual name of the company and then buy "LosAngelesDoctors.org" (or whatever your actual thing is) and then build content linking into your .com site.