Drops in a sensible position (ie, higher than a stock bike is usually set up for) are usually a better choice for longer distances. They offer more hand positions, including several that are more ergonomic than straight bars (palms parallel to your torso vs perpendicular) while still offering braking (and probably shifting) at your fingertips (as opposed to bar ends). But everyone's different. I would strongly suggest trying to find someone you know of similar proportions with a road bike (better yet, a touring-specific road bike) and loaning it from them before you sink serious dough.