Actually road bars with drops have a distinct advantage of flat bars for touring. Road bars allow for a variety of hand positions, and if you have ever toured or participated in distance cycling you would know that multiple hand positions are essential for minimizing hand, wrist, arm, shoulder and neck fatique.

I have a favored position on mine but mix it up over the course of the day and terrain. Flat bars would be a bad idea for touring as you would always have the same hand, writs, arm, neck position, and the hand position on a flat bar is very unnatural.

Trekking bars may offer the same benefit as a road bar in that there are multiple hand positions. I know folks who like the trekking bars...so in the end it does come down to personal preference.