Husband has agreed to go away after New Year in early January

, we will be taking 2 of our sons aged 14 and 11 and possibly our 16 year old. I was wondering if there is any attractions open that will suite my boys on the island at this time of year. We are open to try any of the others islands if it would suit us better.
I would also like to know if it would be cheaper to book now or wait till nearer the time as we aren't tied to any particular place.
Any recomendations of accomodations would be appreciated.
Judith