Some add ons include a stop watch, a calendar and clocks from other time zones or alarms for example, but these items are simply personal preference items.
In summary, finding the perfect sports or fitness watch is a matter of determining how the watch will be used and how it will look and feel on your wrist. Checking the quality level of the watch will be critical unless you are planning to replace the watch periodically. Finally, price of the watch will be an important factor in choosing the ideal sports watch. You may want to think about looking for as quality watch that has been cared for if you want the best quality for the price, but you lose some assurance of the condition of the watch in this instance.
A great sports watch that I use is the Vivofit by Garmin. It is durable, easy to read and has a small profile. For more information on the Garmin Vivofit line of sports watches, click here: