The Dragon Disciple as it is now is perfectly viable. It is a fighter class, and any other combination, though fun and interesting to roleplay, is not optimized.
D12 hd, good fort and will saves, boost to Str, Con, and Cha are all good things. They have really good skill list, for a fighter type. Natural flight and Blindsense are just icing on the cake.
The best combos are things like, Bard1/Barb2/Fighter2, Sor1/Pal4, or combination of PrCs like, Bard1/Ftr4 then into Holy Liberator or Soldier of Light. The reason you take some sort of Divine casting class like Pally or Holy Liberator, is that you can add your bonus spells to those other class, not necessarily your arcane class. So you can get a ton of bless weapons or cure light wounds that you can cast in armor.
Feat selection has to take into account the increase in Str, so things like Power Attack and Improved Trip. Improved Trip is really good since it's just a straight up Strength check.
You also get 3 attacks before Any other class except monk, or 5 attacks if you take 2 weapon fighting. You can always do your bite as a secondary natural attack, along with the iteratives on your weapons. Also, if you have a decent Cha score, with the Class combos I mentioned, you'll be able to get your Cha to saves and pick up divine might. Dex isn't really an important stat, Nor is Wis...
That's all I can think of now.
Daag
D12 hd, good fort and will saves, boost to Str, Con, and Cha are all good things. They have really good skill list, for a fighter type. Natural flight and Blindsense are just icing on the cake.
The best combos are things like, Bard1/Barb2/Fighter2, Sor1/Pal4, or combination of PrCs like, Bard1/Ftr4 then into Holy Liberator or Soldier of Light. The reason you take some sort of Divine casting class like Pally or Holy Liberator, is that you can add your bonus spells to those other class, not necessarily your arcane class. So you can get a ton of bless weapons or cure light wounds that you can cast in armor.
Feat selection has to take into account the increase in Str, so things like Power Attack and Improved Trip. Improved Trip is really good since it's just a straight up Strength check.
You also get 3 attacks before Any other class except monk, or 5 attacks if you take 2 weapon fighting. You can always do your bite as a secondary natural attack, along with the iteratives on your weapons. Also, if you have a decent Cha score, with the Class combos I mentioned, you'll be able to get your Cha to saves and pick up divine might. Dex isn't really an important stat, Nor is Wis...
That's all I can think of now.
Daag