Hey there, I am going for new year with my friend too. I have been twice already this year! I used to live in Playa del Ingles in 2000 and frequently go back and forward so I know it pretty well. Good apartments to stay at with kids are maybe the Bungalows Marbella Golf which are near enough the centre to have fun but far enough out that the kids can sleep at night, pool area is good too and the bungalows are fairly big. Try
http://www.holidaynetwork.co.uk for good prices. Either that or I have stayed in Holanda just outside PDI in maspalomas whixh are nice or the Australia apartments in PDI. These are all suitable for children. I dont have kids so I'm staying at the Los Salmones this year which I wouldnt recommend for kids!!!