Improvements On A Classic Car

We've all seen the negative nellie how to ruin a classic muscle thread or whatever it is. How about a positive spin?

It doesn't have to be an original "muscle car" per say. Might be just a base model like Vixen, my 64 Valiant. But whatever it is, what are some of the things you would do to make it more of what you like?
For my Charger, I have done the following:
Auto dimming rearview mirror with compass.
Extensive sound deadening.
Classic auto air.
Tremec 5 speed.
Electric trunk latch.
AM/FM/CD/MP3 player.
4 wheel power disc brakes.
Battery in trunk.