Don't neglect the various reptilian races, most of which speak Draconic as their native tongue. I can see Dragons fighting a war over the hearts and minds of local Lizardfolk populations, or trying to manipulate the local Kobold tribes.
Gold and Silver half-dragons I can see leaning towards Paladin, or Paladin/Sorceror of a good Human god or Bahamut, and I think all half-dragons would be somewhat inclined towards Sorceror.
The easiest way for the dragon to mold the new allies is to raise them-- either through the voluntary cooperation of the other parent or by enslaving or killing them. Of course, metallic dragons would lean to the former and chromatics to the latter.