IMC we changed the stats of Dragons a bit. Basically, take the MM. Add 8 DEX, and subtract 4 from STR and CON. It's not quite that simple; I do vary it a bit with age (since small dragons are probably more agile) but it's not as severe a change as the STR increases.
Then, when picking their Feats remember to take Combat Reflexes. If the average Ancient Wyrm can take AoOs on the entire party, things get more interesting.
Other DEX-related Feats can be fun, too. Ever seen a Dragon with Whirlwind Attack? *shudder*