You will definitely be there during peak season. I would say that peak season runs from December 15th to April 15th.
We have been there in the months of February, March, April, May, September, November, and December. The only time that I've really seen in "quiet" is in September. Hotter than heck then too!!
Lenbert will run the Bar Crawl any day of the week as long as there are 8 people or more. There are always groups of people to be found no matter what time of the year ..... just find out where the webcasts are when you are there and you will be sure to find a good time!
We have never done Club Mobay and have never waited longer than 45 minutes or so to get off the plane, through customs, pick up luggage, and on our way to Negril.
Respect,
Rina