So watching Episode II with my boys the other night, I think I realized the ship Anakin and Padme leave as refugees to her planet on is a YV-666. Playing X-wing miniatures, I was really looking for the different ships

Are you sure? It isn't listed as such on Wookieepedia (I'm at work, or I'd have checked myself ).

http://starwars.wikia.com/wiki/AA-9_Coruscant_freighter

Stylewise, you would expect them to have been manufactured by the same corporation (Botajef), instead of yet another Corellian ship in case of the YV.

The YV line of CEC ships actually does have a really clear evolution from the standard pie-plate:

Boxified version of iconic CEC round cockpit pod, adapted Consular -class engines:

http://starwars.wikia.com/wiki/YV-100_light_freighter

Further freight-trained:

http://starwars.wikia.com/wiki/YV-330_light_freighter

Weird engines, fins:

http://starwars.wikia.com/wiki/YV-666_light_freighter

Cargo pod/potbelly, possible CR-90 influence, smaller fins:

http://starwars.wikia.com/wiki/YV-929_armed_freighter

Now, the YV-545, 560, and 664 look more pie-plate, but they should honestly be part of the YT line.