Steve Martin as George Jetson?
In this case, I recommend the followings:
* Goldie Hawn as Jane Jetson
* Paris Hilton as Judy Jetson
* Haley Joel Osment as Elroy Jetson.
* St. Bernard from Beethoveen as Astro
* Danny deVito as George's boss
Also, I advise creating Powerpuff Girls live action movie.