Majestic SEO is a completely comprehensive set of enterprise SEO tools that should do the trick at just about any good-sized organization.
It’s main strength, however, is as a link analysis tool (an especially timely quality in the age of the Penguin.) Majestic maintains its own web-crawler that’s comparable to the big search engines.
The value of this to SEOs is that most search engines won’t be sharing this data with the masses, Majestic does. That kind of insight is invaluable to anyone trying to navigate the SEO jungle.
Of course Majestic also offers keyword analysis and all the other basic services you’d expect from enterprise-level SEO software tools.
Majestic offers a number of free services and paid plans run from $49-$399/month.