I purchased a set of aero bars made by Syntace when I began riding my road bike for long distances. I have never removed them (except for a race, where they are not allowed) and find they make riding much more comfortable.
These aero bars were easy to attach to my bicycle's frame and are also removed easily. They do not weigh much, so will not add to the bulk of your cycle.
The Syntace aero bars allow me to get into a more aerodynamic position while riding. They are ergonomically designed, so using them is comfortable. This "aero" position also forces me to use different muscles while riding, which wards off fatigue when pedaling for long periods of time.
The armrests are cushioned and are covered with cloth, so you will not slip if you are sweaty.
I would highly recommend Syntace aero bars if you spend long periods of time on your road bike.