Mayfield Falls isn't crowded and you are way out in the country. It is an easy day trip from Negril. Also, you might want to look at Blue Hole, not far from Negril. If they finally open the hotel it would be a neat place to spend a night or two. Again, way out in the country.
I have been considering a trip to Madeville next time to the island. What is there to do in the area? I know you said "not much", but can you provide any info on interesting things. Perhaps a tour of the mines, or a good museum or maybe some falls in the area?

Regards,
Bob