Happy birthday! And what a great wife to even know what toget you.
You can do anything with it from making your car fully automated, to using it as a not so good paperweight. Choice is yours.
MDX has built in speech control, or you can do RRVoice and MDX COM with RR, or you can do RRFusion (by Sonic) but I do not know how that integrates with RRVoice but I assume it is pretty straightforwards.
I would put a good noise cancelling microphone on your xmas list, like the andrea. The car is noisy, and it is difficult for any mic to work when moving or with the windows down. I would test out the speech window in MDX where it will show you everything the mic heard and what it did and did not accept.