Cazz I noticed you asked about the Waterpark in Ayia Napa on another post. My advice would be to stay in limassol and use their waterpark if your trying to avoid "groups" of single sex partys
As for the older ones being the worst, I'd suggest you don;t tar everyone with the same brush, I suspect you have been frequenting the wrong accommodation if you encounter Club 18-30 type holidaymakers. Pay a little more whether in Cyprus or anywhere else and you wont be "bothered" by people regardless of age having a good time and enjoying themselves.
Don't get me wrong I'm not a big fan of the 18-30 crowd myself but I still know how to party without upseting old fogies and stick in the muds, it's all about respect for the people around you

Wouldn't it be a boring place if we were
ALL the same !
I'm also with Maurice about single young people having far more disposable income than any other group so the flight price wouldn't deter anyone, if anything it would be the long flight time. Most party groups only go for a long weekend and to take in excess of 4 hours of that each way travelling wouldn't really appeal. So you should be safe
Like I said earlier me and 15 friends are off to my villa in Cyprus soon to celebrate my birthday, the ages range from 30 to 50......and we wont be doing pink cowboy hats or any other such tackiness

but we will be having a ball