Whats the best time for a group of 23 to 28 yr olds to travel to cancun,mexico?

One couple has a open trip to the Riu Cancun the rest have to book rooms.
also we were wondering is the nightlife totally dead if your not there during march. Do the other months have a good nightlife?

December through June. The rest is Hurricane season

I am 23 and my cousin and two friends are 21. We just came back from Cancun- We were there the first week of August Thursday to Thursday. It was great. We had a blast and the age group was perfect. I know August just past, but we are already thinking about next August 2008!
It was not too young nor too old with familes every where; it was the perfect age group.
Oasis Palm Beach Resort was amazing!!!

Avoid hurricane season and spring break. I would escape the cold weather here and escape in February.

November is fine, too. August to October is not horrible, especially if you miss the hurricanes, which is typically only 6 or 7 days a year, but unpredictable as to when.