Anyone recommend a Content Management System software that will work well with my existing site

If by "work well with my existing site" you mean "written in CF", Mura is good. If your client has the budget for it, CommonSpot is even better:

http://www.paperthin.com/

But otherwise, it depends on what you mean exactly. What kind of integration do you want between your custom CF applications and your CMS? Same login? Etc.

Dave Watts, CTO, Fig Leaf Software

http://www.figleaf.com/

http://training.figleaf.com/