Add-ons, widgets, and plug-ins
One of the biggest CMS platforms is WordPress, and the reason why it's so big is the number of third-party plug-ins and widgets available. It's free to use and there are tens of thousands of add-ons covering everything from advert management through to "under construction" pages. There are also a huge number of developers and designers who can tweak the platform, to whatever look and feel you require.
When choosing a CMS you should look at what's available now, and look at what you will be needing in the near future. Mobile, video and social media are all things you should be looking at now - no matter what sort of site you are running. Integration into third-party sites such as Facebook - either directly or through an API - should be something that you have on your radar. If these aren't available in the core CMS they should be at least available with a third-party solution.
If possible, talk to the vendor and see what their roadmap includes for future periods, and talk to established users to see how well the vendor has stuck to the roadmap in the past.
Bigger businesses, where there are multiple stakeholders on every project will want the ability to show stakeholders copy before it goes live. However, you don't want to have to send them a screenshot via email every time you make a change, and ideally you won't want them to be able to make changes without an audit trail existing.
A content management system needs the ability for more than one person to use the system at any one time, and will need the ability to have a hierarchy of sign-offs for pages and content.
Inevitably there will be someone who assumes the role of gatekeeper for the content management system. They need the ability to see any content before it goes live, and most importantly they need to be able to see the content as the end-user will see it.
While it's possible to see content and edit it on all CMS systems it's surprising just how many CMS systems don't give you the ability to see a WYSIWYG view of the page. Unless you are a really skilled editor, it's only when you can see the page in situ that you notice some problems.
Search engine optimisation in a CMS
Google loves content, so the ability to have search engine optimisation (SEO) included in the CMS makes sense. It will also save you money compared to the costs of employing an SEO expert.
Most SEO is achieved by linking the content with keywords and key phrases and with content tags into multiple sections of your site. For example a page might be tagged as news, but it could also be tagged as a hardware review, or a feature, and the keywords are likely to be things that describe what the content is about. So the tags and keywords on an early hands-on review on Microsoft's new Surface tablet in a CMS systems would probably be tagged as News and Review, and have would have the keywords, hardware, Microsoft, Microsoft Surface, tablet and mobile.
The keywords and tags could then be automatically used in the page's meta tags for SEO purposes and used as links into further content on the site for readers keen to see alternatives to the Surface.
While external search is important, equally important is an internal search that works. There are many CMS products that have searches that work on keywords only, or that only search on the headlines and standfirsts. Searches should allow an end-user to search all the content in the CMS, with words and phrases. Ideally searches should also be able to be refined, so that users can see content that was for example produced in the last week, or month or was just in a particular tag ike a review or had a certain keyword.