CMS Website development for professional services startup

website design and development for a legal services start up based in the City of London. A mind map image detailing the pages and navigation is attached together with the company logo. The site will aim to serve three sorts of constituents / clients - Corporate Lawyers, Law Firms and Government Regulators. It should be constructed using a popular CMS tool so that it may be updated by the owner once the design is complete. The site will incorporate a gallery with a a few images / key messages about the company (ABS Exchange Limited). Here are some sites which have the look and feel I am seeking:

http://thomsonreuters.com/

http://www.bg-group.com/

http://www.centrica.com/

http://www.linkilaters.com/

http://www.dlapiper.com/

http://www.clydeco.com/