Our family loved the Sunwing Bangtao. The happy baby studio was fantastic with young kids, located on the ground floor with a little yard with table and chairs and 2 sun loungers. There were a range of pools of differing depth/size, including baby and younger children's pools, through to deep, and of course a great waterslide. The restaurant was good and decent value for money. Grounds and pool kept well.
Negatives were that there weren't enough sunloungers around the main pools where kids are, the smoking zone was located on main path to lobby, the restaurant kids buffet wasn't open at dinner (maybe being low season but my eldest loves it at the Kamala Sunwing), it was a bit far walking distance from the town, plus no footpath, so a little scary (and the little tuk tuks in this area of phuket didn't seem big enough to take the pram) so a shuttle might have been good, however there was a great restaurant across the road and if the tide was out quite a few beach restaurants. The kids club was on the average side and you couldn't check children in like at Kamala and other resorts in phuket we've been to. But the babysitting service at kids club was great and the kids loved their babysitter. And my main criticism is that the nightly entertainment was virtually non-existant. I know we went in low season, but I really think they could just have acoustic singers for an hour or two (8-10ish), so parents can have a cocktail after dinner and the kids dance, they had this at the Centara Karon and the nights were a lot more enjoyable for the parents! I think they could do better here and it would probably encourage families to stay at the resort and spend more at the bar.