I know I repeat myself and sorry if I'm heavy but I'd like to share this: if what you want is a familiar kind of workflow to avoid a starting-from-zero learning curve, I'd go for AE. It's good, it works and there is a lot of tutorial everywhere on the internet.
But if you really want something more solid, check Autodesk. Even the rather "old" Combustion. It is another planet.
Color grading and keying (and 3D) are in another league. The downside is that you really need to learn from zero and there is almost no help in internet.
But Chris, if you are with FCP, they will release at one point the new version and now why not going with Smoke application? (and get rid-of all the other softwares and plug-ins etc...)
Color grading with Autodesk Smoke (combustion is very similar) and no need the Euphonix: http://www.youtube.com/watch?v=NAwO6znerkc
The Color Corrector setups you create in Combustion are compatible with the Color Corrector setups in the following Autodesk systems: Flint, Flame, Inferno, Smoke, and Fire.
and sound: http://www.youtube.com/watch?v=YOaUhf68eN0&feature=related