You might consider taking an excursion to the world famous Pelican Bar, which is often combined with the Black River Safari, Appleton's rum tour or a trip to Y.S. Falls. Many people also like Mayfield Falls. Both of these waterfalls are much closer than Dunns River Falls, which is a pretty long drive from Negril.
Some folks like to visit one of the tourist bars on the West End Cliffs for a different view of one of the awesome Negril sunsets, or perhaps just to watch the locals cliff diving.
The tour desk at CSA can help you to arrange any of these excursions.